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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. void solve() {
  5. 	int n;
  6. 	cin >> n;
  7. 	vector<int> a(n);
  8. 	for (int i = 0; i < n; i++) cin >> a[i];
  9. 	sort(a.begin(), a.end());
  10. 	unordered_map<int, int> freq;
  11. 	for (int i = 0; i < n; i++) {
  12. 		freq[a[i]]++;
  13. 	}
  14. 	int l = 0, r = n - 1;
  15. 	while (l < r && r >= 0 && l < n) {
  16. 		if (freq[a[r]] % 2 == 0) {
  17. 			r--;
  18. 		} else {
  19. 			if (freq[a[l]] == 1) {
  20. 				cout << "NO" << endl;
  21. 				return;
  22. 			} else if (freq[a[l]] % 2 == 0) {
  23. 				l++;
  24. 			} else {
  25. 				l++;
  26. 				r--;
  27. 				freq[a[l]]--;
  28. 				freq[a[r]]--;
  29. 			}
  30. 		}
  31. 	}
  32. 	if (l == r) {
  33.  
  34. 		if (freq[a[l]] % 2 == 1) {
  35. 			cout << "NO" << endl;
  36. 		} else {
  37. 			cout << "YES" << endl;
  38. 		}
  39. 	} else {
  40. 		cout << "YES" << endl;
  41. 	}
  42. }
  43.  
  44. int main() {
  45. 	int t;
  46. 	cin >> t;
  47. 	while (t--) solve();
  48. }
Success #stdin #stdout 0.01s 5284KB
comments (?)
stdin
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9
2
1 1
2
2 1
4
1 1 4 4
4
3 4 3 3
4
2 3 4 4
6
3 3 4 5 3 3
6
2 2 2 4 4 4
8
1 1 1 1 1 1 1 4
10
9 9 9 10 10 10 10 10 10 10
stdout
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YES
NO
YES
NO
NO
NO
YES
NO
YES
https://ideone.com/0QAXlO
language:
C++14 (gcc 8.3)
created:
11 days ago
visibility:
public

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