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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int main() {
  5.  
  6.     int tc;
  7.     cin >> tc;
  8.  
  9.     while (tc--) {
  10.         int n;
  11.         cin >> n;
  12.         string s;
  13.         cin >> s;
  14.  
  15.         int cA = 0, cB = 0;
  16.         for (char c : s) {
  17.             if (c == 'a') cA++;
  18.             else cB++;
  19.         }
  20.  
  21.         int d = cB - cA;
  22.  
  23.         if (d == 0) {
  24.             cout << 0 << "\n";
  25.             continue;
  26.         }
  27.  
  28.         vector<int> a(n);
  29.         for (int i = 0; i < n; i++) {
  30.             a[i] = (s[i] == 'a') ? -1 : 1;
  31.         }
  32.  
  33.         int pref = 0;
  34.         int ans = INT_MAX;
  35.         unordered_map<int, int> mp;
  36.         mp[pref] = -1;
  37.  
  38.         for (int i = 0; i < n; i++) {
  39.             pref += a[i];
  40.             int complement = pref - d;
  41.  
  42.             if (mp.find(complement) != mp.end()) {
  43.                 ans = min(ans, i - mp[complement]);
  44.             }
  45.  
  46.             mp[pref] = i;
  47.         }
  48.  
  49.         if (ans == n || ans == INT_MAX)
  50.             cout << -1 << "\n";
  51.         else
  52.             cout << ans << "\n";
  53.     }
  54.  
  55.     return 0;
  56. }
  57.  
Success #stdin #stdout 0s 5308KB
comments (?)
stdin
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5
5
bbbab
6
bbaaba
4
aaaa
12
aabbaaabbaab
5
aabaa
stdout
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3
0
-1
2
-1
https://ideone.com/28nU6j
language:
C++ (gcc 8.3)
created:
2 days ago
visibility:
public

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