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Shivam010Shivam010
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Solve 024
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7 files changed

+314
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‎023/code.cpp

-4
Original file line numberDiff line numberDiff line change
@@ -20,10 +20,6 @@ For example, given the following board:
2020
[f, f, f, f],
2121
[f, f, f, f]]
2222
```
23-
0 1 2 3
24-
4 5 6 7
25-
8 9 10 11
26-
12 13 14 15
2723
2824
and start = (3, 0) (bottom left) and end = (0, 0) (top left), the minimum number
2925
of steps required to reach the end is 7, since we would need to go through (1,

‎024/code.cpp

+141-8
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,23 @@
11
/*
22
Daily Coding Challenge #024
33
---------------------------
4+
This problem was asked by Google.
45
6+
Implement locking in a binary tree. A binary tree node can be locked or unlocked
7+
only if all of its descendants or ancestors are not locked.
8+
9+
Design a binary tree node class with the following methods:
10+
11+
- `is_locked`, which returns whether the node is locked.
12+
- `lock`, which attempts to lock the node. If it cannot be locked, then it
13+
should return false. Otherwise, it should lock it and return true.
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- `unlock`, which unlocks the node. If it cannot be unlocked, then it should
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return false. Otherwise, it should unlock it and return true.
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You may augment the node to add parent pointers or any other property you would
18+
like. You may assume the class is used in a single-threaded program, so there is
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no need for actual locks or mutexes. Each method should run in `O(h)`, where `h`
20+
is the height of the tree.
521
622
Run Using
723
---------
@@ -11,15 +27,132 @@ g++ 024/code.cpp -o bin/out && ./bin/out < 024/in.txt > 024/out.txt
1127
using namespace std;
1228
#define ll long long
1329

14-
void solve() {
15-
int n;
16-
return;
30+
struct Node {
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// val: value of node
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int val;
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// stats for locked nodes
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bool state; // true for lock
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int leftLocks; // no. of left sub-tree nodes that are locked
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int rightLocks; // no. of right sub-tree nodes that are locked
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Node *parent; // parent node
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Node *left, *right; // children nodes
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Node(Node *par, int v) {
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parent = par;
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val = v;
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state = false;
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leftLocks = rightLocks = 0;
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left = right = NULL;
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}
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bool is_locked() { return state; }
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bool lock() {
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Node *tmp = this;
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bool already = (state+leftLocks + rightLocks > 0);
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while (tmp->parent && !already) {
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tmp = tmp->parent;
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already = tmp->state;
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}
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if (already) {
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cout << "(already locked due to: " << tmp->val
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<< " is_locked:" << (tmp->state ? "true" : "false")
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<< " leftLocks:" << tmp->leftLocks
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<< " rightLocks:" << tmp->rightLocks << ") ";
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return false;
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}
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// the node or its parent are not locked, means the children are also
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// not locked and the current node is free to be locked
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state = true; // lock node
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// set child lock for parents
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tmp = this;
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Node *par = tmp->parent;
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while (par) {
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if (par->left == tmp)
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par->leftLocks++;
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else
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par->rightLocks++;
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tmp = par;
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par = par->parent;
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}
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return true;
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}
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bool unlock() {
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if (!state) return false;
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state = false; // unlock it
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// update parent stats
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Node *tmp = this, *par = tmp->parent;
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while (par) {
89+
if (par->left == tmp)
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par->leftLocks--;
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else
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par->rightLocks--;
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tmp = par;
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par = par->parent;
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}
96+
return true;
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}
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};
99+
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void PrintTree(Node *root, string prefix) {
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if (root->right != NULL) PrintTree(root->right, prefix + "\t");
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cout << prefix << root->val << endl;
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if (root->left != NULL) PrintTree(root->left, prefix + "\t");
17104
}
18105

19-
int main() {
20-
int t;
21-
cin >> t;
22-
while (t--) {
23-
solve();
106+
void ScanTree(int n, Node **list) {
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for (int i = 0; i < n; i++) {
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list[i] = NULL;
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}
110+
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n--;
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while (n--) {
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int x, y;
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cin >> x >> y; // x is parent of y
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if (list[x] == NULL) list[x] = new Node(NULL, x);
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if (list[y] == NULL) list[y] = new Node(list[x], y);
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list[y]->parent = list[x];
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if (list[x]->left == NULL)
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list[x]->left = list[y];
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else
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list[x]->right = list[y];
24122
}
25123
}
124+
125+
void solve() {
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int n; // nodes
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cin >> n;
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Node *root, *list[n];
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ScanTree(n, list);
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// considering 0 as root
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root = list[0];
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PrintTree(root, "");
133+
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int q; // queries
135+
cin >> q;
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string op; // operation
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int on; // on: node index
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bool res; // response
140+
141+
while (q--) {
142+
cin >> op >> on;
143+
cout << op << " " << on << " ";
144+
if (op == "lock")
145+
res = list[on]->lock();
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else if (op == "unlock")
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res = list[on]->unlock();
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else
149+
res = list[on]->is_locked();
150+
if (res)
151+
cout << "true" << endl;
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else
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cout << "false" << endl;
154+
}
155+
return;
156+
}
157+
158+
int main() { solve(); }

‎024/code.py

-13
This file was deleted.

‎024/in.txt

+87-1
Original file line numberDiff line numberDiff line change
@@ -1 +1,87 @@
1-
1+
21
2+
0 2
3+
0 3
4+
2 1
5+
2 4
6+
3 7
7+
3 8
8+
8 9
9+
8 10
10+
9 17
11+
4 6
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1 5
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5 11
14+
5 12
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11 18
16+
18 20
17+
6 13
18+
14 16
19+
16 19
20+
6 14
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13 15
22+
65
23+
lock 6
24+
is_locked 6
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lock 13
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is_locked 13
27+
unlock 13
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lock 16
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is_locked 16
30+
unlock 6
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lock 13
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lock 14
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is_locked 13
34+
is_locked 14
35+
lock 4
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is_locked 4
37+
lock 1
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is_locked 1
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lock 1
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is_locked 1
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unlock 14
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lock 15
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unlock 13
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lock 15
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lock 6
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unlock 6
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lock 0
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unlock 1
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lock 0
50+
unlock 15
51+
lock 0
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lock 2
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unlock 0
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lock 2
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lock 7
56+
is_locked 2
57+
is_locked 7
58+
lock 18
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lock 19
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unlock 2
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lock 19
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lock 18
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lock 20
64+
is_locked 20
65+
is_locked 18
66+
is_locked 19
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lock 13
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is_locked 13
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lock 9
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is_locked 9
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unlock 13
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lock 10
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is_locked 10
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unlock 9
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unlock 10
76+
unlock 7
77+
lock 3
78+
is_locked 3
79+
lock 0
80+
is_locked 0
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unlock 3
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lock 0
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unlock 19
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lock 0
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unlock 18
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lock 0
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is_locked 0

‎024/out.txt

+86-1
Original file line numberDiff line numberDiff line change
@@ -1 +1,86 @@
1-
1+
10
2+
8
3+
9
4+
17
5+
3
6+
7
7+
0
8+
4
9+
14
10+
16
11+
19
12+
6
13+
13
14+
15
15+
2
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1
17+
12
18+
5
19+
11
20+
18
21+
20
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lock 6 true
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is_locked 6 true
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lock 13 (already locked due to: 6 is_locked:true leftLocks:0 rightLocks:0) false
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is_locked 13 false
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unlock 13 false
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lock 16 (already locked due to: 6 is_locked:true leftLocks:0 rightLocks:0) false
28+
is_locked 16 false
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unlock 6 true
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lock 13 true
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lock 14 true
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is_locked 13 true
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is_locked 14 true
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lock 4 (already locked due to: 4 is_locked:false leftLocks:2 rightLocks:0) false
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is_locked 4 false
36+
lock 1 true
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is_locked 1 true
38+
lock 1 (already locked due to: 1 is_locked:true leftLocks:0 rightLocks:0) false
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is_locked 1 true
40+
unlock 14 true
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lock 15 (already locked due to: 13 is_locked:true leftLocks:0 rightLocks:0) false
42+
unlock 13 true
43+
lock 15 true
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lock 6 (already locked due to: 6 is_locked:false leftLocks:1 rightLocks:0) false
45+
unlock 6 false
46+
lock 0 (already locked due to: 0 is_locked:false leftLocks:2 rightLocks:0) false
47+
unlock 1 true
48+
lock 0 (already locked due to: 0 is_locked:false leftLocks:1 rightLocks:0) false
49+
unlock 15 true
50+
lock 0 true
51+
lock 2 (already locked due to: 0 is_locked:true leftLocks:0 rightLocks:0) false
52+
unlock 0 true
53+
lock 2 true
54+
lock 7 true
55+
is_locked 2 true
56+
is_locked 7 true
57+
lock 18 (already locked due to: 2 is_locked:true leftLocks:0 rightLocks:0) false
58+
lock 19 (already locked due to: 2 is_locked:true leftLocks:0 rightLocks:0) false
59+
unlock 2 true
60+
lock 19 true
61+
lock 18 true
62+
lock 20 (already locked due to: 18 is_locked:true leftLocks:0 rightLocks:0) false
63+
is_locked 20 false
64+
is_locked 18 true
65+
is_locked 19 true
66+
lock 13 true
67+
is_locked 13 true
68+
lock 9 true
69+
is_locked 9 true
70+
unlock 13 true
71+
lock 10 true
72+
is_locked 10 true
73+
unlock 9 true
74+
unlock 10 true
75+
unlock 7 true
76+
lock 3 true
77+
is_locked 3 true
78+
lock 0 (already locked due to: 0 is_locked:false leftLocks:2 rightLocks:1) false
79+
is_locked 0 false
80+
unlock 3 true
81+
lock 0 (already locked due to: 0 is_locked:false leftLocks:2 rightLocks:0) false
82+
unlock 19 true
83+
lock 0 (already locked due to: 0 is_locked:false leftLocks:1 rightLocks:0) false
84+
unlock 18 true
85+
lock 0 true
86+
is_locked 0 true

‎go.mod

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@@ -1,8 +1,3 @@
11
module github.com/Shivam010/daily-coding-problem
22

33
go 1.14
4-
5-
require (
6-
github.com/gomarkdown/markdown v0.0.0-20200824053859-8c8b3816f167 // indirect
7-
github.com/gomarkdown/mdtohtml v0.0.0-20180202094705-7346712f31b4 // indirect
8-
)

‎go.sum

-5
This file was deleted.

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