special array ...

Author: geeky01adarsh

README.md

@@ -5,5 +5,5 @@
 | S.No. | Topic | Status |
 |---|--------------|-----|
 |01. | [Array](/Arrays) | 24/28 |
-|02. | [Searching](/Searching)|15/38|
+|02. | [Searching](/Searching)|16/38|
 |03. | [Sorting](/Sorting)|0/38|

Searching/README.md

@@ -17,7 +17,7 @@
 |12| [Intersection of Two Arrays II](https://leetcode.com/problems/intersection-of-two-arrays-ii/)|[Solution](intersection_of_two_arrays_ii.cpp)|
 |13| [Fair Candy Swap](https://leetcode.com/problems/fair-candy-swap/)|Pending|
 |14| [Check If N and Its Double Exist](https://leetcode.com/problems/check-if-n-and-its-double-exist/)|[Solution](check_if_n_and_its_double_exist.cpp)|
-|15| [Special Array With X Elements Greater Than or Equal X](https://leetcode.com/problems/special-array-with-x-elements-greater-than-or-equal-x/)|Pending|
+|15| [Special Array With X Elements Greater Than or Equal X](https://leetcode.com/problems/special-array-with-x-elements-greater-than-or-equal-x/)|[Solution](special_array_with_x_elements_greater_than_or_equal_x.cpp)|
 |16| [Binary Search](https://leetcode.com/problems/binary-search/)|[Solution](binary_search.cpp)|
 |17| [Guess Number Higher or Lower](https://leetcode.com/problems/guess-number-higher-or-lower/)|[Solution](guess_no_higher_lower.cpp)|
 

Searching/special_array_with_x_elements_greater_than_or_equal_x.cpp

@@ -0,0 +1,43 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int specialArray(vector<int> &nums)
+{
+    // with complexity O(n log(n))
+    //      sort(nums.begin(), nums.end());  // O(NlogN)
+    // const int N = nums.size();
+    // if (nums[0] >= N) return N;
+    // int l = 1, r = N - 1;
+    // while (l <= r) { // O(LogN) * O(1)
+    //     int m = l + (r - l) / 2;
+    //     if (nums[m] >= (N - m) && nums[m - 1] < (N - m)) return (N - m);
+    //     else if (nums[m] >= (N - m)) r = m - 1;
+    //     else l = m + 1;
+    // }
+    // return -1;
+
+    // counting sort
+    int count[102] = {0}, N = nums.size();
+    for (int n : nums)
+        count[min(n, N)]++;
+    for (int i = N; i >= 0; i--)
+    {
+        count[i] = count[i + 1] + count[i];
+        if (count[i] == i)
+            return i;
+    }
+    return -1;
+}
+
+int main()
+{
+    int n;
+    cin>>n;
+    vector<int> v;
+    for(int i=0; i<n; i++){
+        int temp; cin>>temp;
+        v.push_back(temp);
+    }
+    cout<<specialArray(v)<<endl;
+    return 0;
+}