Codeforces Round 865 (Div. 2) 1816C. Ian and Array Sorting Solution

 

Problem Link : https://codeforces.com/contest/1816/problem/C

Solution in C++:

1. /// Author : AH_Tonmoy
2. #include <bits/stdc++.h>
3. using namespace std;
4. int32_t main() {
5. ios_base::sync_with_stdio(0);
6. cin.tie(0);
7. int t;
8. cin >> t;
9. while (t--) {
10. int n;
11. cin >> n;
12. vector<long long> a(n);
13. for (int i = 0; i < n; i++) {
14. cin >> a[i];
15. }
16. for (int i = 1; i < n - 1; i++) {
17. if (a[i] < a[i - 1]) {
18. a[i + 1] +=(a[i - 1] - a[i]);
19. a[i] = a[i - 1];
20. }
21. }
22. for (int i = n - 2; i > 0; i--) {
23. if (a[i] > a[i + 1]) {
24. a[i - 1] -= (a[i] - a[i + 1]);
25. a[i] = a[i + 1];
26. }
27. }
28. if (is_sorted(a.begin(), a.end()))
29. cout << "YES" << endl;
30. else
31. cout << "NO" << endl;
32. }
33. }