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MaskRayMaskRay
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‎README.md

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22

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[LeetCode solutions](http://maskray.me/blog/2014-06-29-leetcode-solutions) gives some thoughts on selected problems.
44

5-
Solved 406/421 problems.
5+
Solved 418/421 problems.
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## Database
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@@ -13,11 +13,21 @@ See [database.md](database.md)
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| # | Title | Solution |
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|---| ----- | -------- |
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|453|[Minimum Moves to Equal Array Elements](https://leetcode.com/problems/minimum-moves-to-equal-array-elements)|[minimum-moves-to-equal-array-elements.cc](minimum-moves-to-equal-array-elements.cc)|
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|452|[Minimum Number of Arrows to Burst Balloons](https://leetcode.com/problems/minimum-number-of-arrows-to-burst-balloons)|[minimum-number-of-arrows-to-burst-balloons.cc](minimum-number-of-arrows-to-burst-balloons.cc)|
1617
|447|[Number of Boomerangs](https://leetcode.com/problems/number-of-boomerangs)|[number-of-boomerangs.cc](number-of-boomerangs.cc)|
18+
|446|[Arithmetic Slices II - Subsequence](https://leetcode.com/problems/arithmetic-slices-ii-subsequence)|[arithmetic-slices-ii-subsequence.cc](arithmetic-slices-ii-subsequence.cc)|
19+
|444|[Sequence Reconstruction](https://leetcode.com/problems/sequence-reconstruction)|[sequence-reconstruction.cc](sequence-reconstruction.cc)|
20+
|441|[Arranging Coins](https://leetcode.com/problems/arranging-coins)|[arranging-coins.cc](arranging-coins.cc)|
21+
|440|[K-th Smallest in Lexicographical Order](https://leetcode.com/problems/k-th-smallest-in-lexicographical-order)|[k-th-smallest-in-lexicographical-order.cc](k-th-smallest-in-lexicographical-order.cc)|
22+
|439|[Ternary Expression Parser](https://leetcode.com/problems/ternary-expression-parser)|[ternary-expression-parser.cc](ternary-expression-parser.cc)|
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|438|[Find All Anagrams in a String](https://leetcode.com/problems/find-all-anagrams-in-a-string)|[find-all-anagrams-in-a-string.cc](find-all-anagrams-in-a-string.cc)|
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|437|[Path Sum III](https://leetcode.com/problems/path-sum-iii)|[path-sum-iii.cc](path-sum-iii.cc)|
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|436|[Find Right Interval](https://leetcode.com/problems/find-right-interval)|[find-right-interval.cc](find-right-interval.cc)|
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|435|[Non-overlapping Intervals](https://leetcode.com/problems/non-overlapping-intervals)|[non-overlapping-intervals.cc](non-overlapping-intervals.cc)|
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|432|[All O`one Data Structure](https://leetcode.com/problems/all-oone-data-structure)|[all-oone-data-structure.cc](all-oone-data-structure.cc)|
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|424|[Longest Repeating Character Replacement](https://leetcode.com/problems/longest-repeating-character-replacement)|[longest-repeating-character-replacement.cc](longest-repeating-character-replacement.cc)|
29+
|423|[Reconstruct Original Digits from English](https://leetcode.com/problems/reconstruct-original-digits-from-english)|[reconstruct-original-digits-from-english.cc](reconstruct-original-digits-from-english.cc)|
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|422|[Valid Word Square](https://leetcode.com/problems/valid-word-square)|[valid-word-square.cc](valid-word-square.cc)|
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|421|[Maximum XOR of Two Numbers in an Array](https://leetcode.com/problems/maximum-xor-of-two-numbers-in-an-array)|[maximum-xor-of-two-numbers-in-an-array.cc](maximum-xor-of-two-numbers-in-an-array.cc)|
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|420|[Strong Password Checker](https://leetcode.com/problems/strong-password-checker)|[strong-password-checker.cc](strong-password-checker.cc)|
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|419|[Battleships in a Board](https://leetcode.com/problems/battleships-in-a-board)|[battleships-in-a-board.cc](battleships-in-a-board.cc)|
@@ -29,6 +39,8 @@ See [database.md](database.md)
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|412|[Fizz Buzz](https://leetcode.com/problems/fizz-buzz)|[fizz-buzz.cc](fizz-buzz.cc)|
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|410|[Split Array Largest Sum](https://leetcode.com/problems/split-array-largest-sum)|[split-array-largest-sum.cc](split-array-largest-sum.cc)|
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|409|[Longest Palindrome](https://leetcode.com/problems/longest-palindrome)|[longest-palindrome.cc](longest-palindrome.cc)|
42+
|408|[Valid Word Abbreviation](https://leetcode.com/problems/valid-word-abbreviation)|[valid-word-abbreviation.cc](valid-word-abbreviation.cc)|
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|407|[Trapping Rain Water II](https://leetcode.com/problems/trapping-rain-water-ii)|[trapping-rain-water-ii.cc](trapping-rain-water-ii.cc)|
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|406|[Queue Reconstruction by Height](https://leetcode.com/problems/queue-reconstruction-by-height)|[queue-reconstruction-by-height.cc](queue-reconstruction-by-height.cc)|
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|405|[Convert a Number to Hexadecimal](https://leetcode.com/problems/convert-a-number-to-hexadecimal)|[convert-a-number-to-hexadecimal.cc](convert-a-number-to-hexadecimal.cc)|
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|404|[Sum of Left Leaves](https://leetcode.com/problems/sum-of-left-leaves)|[sum-of-left-leaves.cc](sum-of-left-leaves.cc)|

‎all-oone-data-structure.cc

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// All O`one Data Structure
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class AllOne {
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struct Bucket { int v; unordered_set<string> ks; };
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unordered_map<string, list<Bucket>::iterator> a;
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list<Bucket> b;
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public:
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/** Initialize your data structure here. */
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AllOne() {
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b.push_front({0, {}});
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}
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/** Inserts a new key <Key> with value 1. Or increments an existing key by 1. */
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void inc(string key) {
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if (! a.count(key)) {
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a[key] = b.begin();
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b.begin()->ks.insert(key);
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}
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auto y = a[key], x = y++;
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if (y == b.end() || x->v+1 < y->v)
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y = b.insert(y, {x->v+1, {}});
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a[key] = y;
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y->ks.insert(key);
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x->ks.erase(key);
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if (x->ks.empty() && x->v)
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b.erase(x);
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}
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/** Decrements an existing key by 1. If Key's value is 1, remove it from the data structure. */
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void dec(string key) {
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if (a.count(key)) {
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auto y = a[key], x = y--;
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if (x->v > 1) {
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if (x == b.begin() || y->v < x->v-1)
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y = b.insert(x, {x->v-1, {}});
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a[key] = y;
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y->ks.insert(key);
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} else
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a.erase(key);
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x->ks.erase(key);
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if (x->ks.empty())
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b.erase(x);
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}
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}
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/** Returns one of the keys with maximal value. */
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string getMaxKey() {
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return b.size() == 1 ? "" : *b.rbegin()->ks.begin();
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}
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/** Returns one of the keys with Minimal value. */
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string getMinKey() {
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return b.size() == 1 ? "" : *(++b.begin())->ks.begin();
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}
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};
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/**
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* Your AllOne object will be instantiated and called as such:
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* AllOne obj = new AllOne();
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* obj.inc(key);
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* obj.dec(key);
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* string param_3 = obj.getMaxKey();
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* string param_4 = obj.getMinKey();
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*/

‎arithmetic-slices-ii-subsequence.cc

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// Arithmetic Slices II - Subsequence
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class Solution {
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public:
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int numberOfArithmeticSlices(vector<int>& A) {
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int r = 0;
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vector<unordered_map<long, int>> s(A.size());
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for (int i = 1; i < A.size(); i++)
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for (int j = 0; j < i; j++) {
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long d = long(A[i])-A[j];
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if (s[j].count(d)) {
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r += s[j][d];
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s[i][d] += s[j][d];
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}
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s[i][d]++;
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}
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return r;
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}
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};

‎arranging-coins.cc

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// Arranging Coins
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class Solution {
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public:
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int arrangeCoins(int n) {
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return sqrt(2.*n+0.25)-0.5;
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}
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};

‎k-th-smallest-in-lexicographical-order.cc

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// K-th Smallest in Lexicographical Order
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class Solution {
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public:
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int findKthNumber(int n, int k) {
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long r = 1;
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while (k > 1) {
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long c = 0, x = r, y = r+1;
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for (; x <= n; x *= 10, y *= 10)
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c += min(n+1L, y)-x;
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if (c < k)
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k -= c, r++;
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else
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k--, r *= 10;
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}
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return r;
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}
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};

‎longest-repeating-character-replacement.cc

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// Longest Repeating Character Replacement
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class Solution {
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public:
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int characterReplacement(string s, int k) {
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int x = 0, mx = 0, c[127] = {};
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for (int i = 0; i < s.size(); i++) {
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mx = max(mx, ++c[s[i]]);
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if (mx+k <= i-x)
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c[s[x++]]--;
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}
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return s.size()-x;
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}
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};

‎minimum-number-of-arrows-to-burst-balloons.cc

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// Minimum Number of Arrows to Burst Balloons
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class Solution {
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public:
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int findMinArrowShots(vector<pair<int, int>>& points) {
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int r = 0;
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sort(points.begin(), points.end(), [](const pair<int, int>& x, const pair<int, int>& y) {
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return x.second < y.second;
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});
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for (int i = 0; i < points.size(); ) {
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r++;
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int t = points[i].second;
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while (++i < points.size() && points[i].first <= t);
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}
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return r;
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}
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};

‎reconstruct-original-digits-from-english.cc

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// Reconstruct Original Digits from English
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class Solution {
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public:
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string originalDigits(string s) {
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int c[127] = {}, a[10];
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for (char i: s)
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c[i]++;
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a[0] = c['z'];
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a[2] = c['w'];
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a[4] = c['u'];
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a[6] = c['x'];
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a[8] = c['g'];
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a[1] = c['o']-a[0]-a[2]-a[4];
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a[3] = c['h']-a[8];
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a[5] = c['f']-a[4];
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a[7] = c['v']-a[5];
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a[9] = c['i']-a[5]-a[6]-a[8];
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string r;
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for (int i = 0; i < 10; i++)
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r += string(a[i], '0'+i);
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return r;
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}
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};

‎sequence-reconstruction.cc

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// Sequence Reconstruction
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#define FOR(i, a, b) for (remove_cv<remove_reference<decltype(b)>::type>::type i = (a); i < (b); i++)
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#define REP(i, n) FOR(i, 0, n)
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class Solution {
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public:
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bool sequenceReconstruction(vector<int>& org, vector<vector<int>>& seqs) {
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int n = org.size();
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vector<int> d(n, 0);
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vector<char> v(n, 0);
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vector<vector<int>> e(n);
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for (auto& seq: seqs) {
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for (int i: seq) {
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if (i <= 0 || i > n)
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return false;
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v[i-1] = 1;
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}
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REP(i, int(seq.size())-1) {
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e[seq[i]-1].push_back(seq[i+1]-1);
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d[seq[i+1]-1]++;
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}
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}
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if (count(v.begin(), v.end(), 0))
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return false;
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int r = 0, l = 0, x = -1;
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REP(i, n)
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if (! d[i]) {
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if (x >= 0) return false;
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x = i;
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}
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while (x >= 0) {
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if (x != org[l++]-1) return false;
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int u = x;
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x = -1;
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for (int y: e[u])
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if (! --d[y]) {
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if (x >= 0) return false;
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x = y;
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}
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}
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return l == n;
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}
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};

‎ternary-expression-parser.cc

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// Ternary Expression Parser
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class Solution {
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string f(string& e, int& i) {
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char a = e[i];
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i += 2;
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if (i-1 == e.size() || e[i-1] != '?')
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return string(1, a);
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string l = f(e, i), r = f(e, i);
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return a == 'T' ? l : r;
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}
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public:
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string parseTernary(string expression) {
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int i = 0;
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return f(expression, i);
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}
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};

‎trapping-rain-water-ii.cc

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// Trapping Rain Water II
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#define FOR(i, a, b) for (remove_cv<remove_reference<decltype(b)>::type>::type i = (a); i < (b); i++)
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#define REP(i, n) FOR(i, 0, n)
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class Solution {
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public:
7+
int trapRainWater(vector<vector<int>>& h) {
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if (h.size() < 3 || h[0].size() < 3) return 0;
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int r = 0, m = h.size(), n = h[0].size(), x, y;
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vector<vector<char>> v(m, vector<char>(n, 0));
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vector<vector<pair<int, int>>> s(20001);
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REP(i, m) {
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s[h[i][0]].emplace_back(i, 0);
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s[h[i][n-1]].emplace_back(i, n-1);
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v[i][0] = v[i][n-1] = 1;
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}
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FOR(i, 1, n) {
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s[h[0][i]].emplace_back(0, i);
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s[h[m-1][i]].emplace_back(m-1, i);
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v[0][i] = v[m-1][i] = 1;
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}
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REP(i, s.size())
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while (s[i].size()) {
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tie(x, y) = s[i].back();
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s[i].pop_back();
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REP(d, 4) {
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int xx = x+((int[]){-1,0,1,0})[d], yy = y+((int[]){0,1,0,-1})[d];
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if (unsigned(xx) < m && unsigned(yy) < n && ! v[xx][yy]) {
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v[xx][yy] = 1;
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int t = max(h[x][y], h[xx][yy]);
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r += t-h[xx][yy];
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h[xx][yy] = t;
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s[t].emplace_back(xx, yy);
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}
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}
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}
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return r;
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}
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};

‎valid-word-abbreviation.cc

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// Valid Word Abbreviation
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class Solution {
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public:
4+
bool validWordAbbreviation(string word, string abbr) {
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int j = 0;
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for (int i = 0; i < abbr.size(); ) {
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if (j >= word.size())
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return false;
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if (isdigit(abbr[i])) {
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if (abbr[i] == '0') return false;
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int t = abbr[i]-'0';
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while (++i < abbr.size() && isdigit(abbr[i])) {
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t = t*10+abbr[i]-'0';
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if (j+t > word.size()) return false;
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}
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j += t;
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} else if (abbr[i++] != word[j++])
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return false;
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}
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return j == word.size();
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}
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};

‎valid-word-square.cc

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// Valid Word Square
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class Solution {
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public:
4+
bool validWordSquare(vector<string>& words) {
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int n = words.size();
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if (! n) return true;
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int m = words[0].size();
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if (n != m) return false;
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for (int i = 1; i < n; i++)
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if (words[i-1].size() < words[i].size())
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return false;
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for (int i = 0; i < n; i++)
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for (int j = 0; j < words[i].size(); j++)
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if (words[j].size() <= i || words[i][j] != words[j][i])
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return false;
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return true;
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}
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};

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