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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int solve_for(char king, const string &s) {
  5.     int n = s.size();
  6.     vector<int> pref(n + 1, 0);
  7.  
  8.     for (int i = 1; i <= n; i++) {
  9.         if (s[i - 1] == king) pref[i] = pref[i - 1] + 1;
  10.         else pref[i] = pref[i - 1] - 1;
  11.     }
  12.  
  13.     vector<int> minPref(n + 1), pos(n + 1);
  14.     minPref[0] = pref[0];
  15.     pos[0] = 0;
  16.  
  17.     for (int i = 1; i <= n; i++) {
  18.         if (pref[i] < minPref[i - 1]) {
  19.             minPref[i] = pref[i];
  20.             pos[i] = i;
  21.         } else {
  22.             minPref[i] = minPref[i - 1];
  23.             pos[i] = pos[i - 1];
  24.         }
  25.     }
  26.  
  27.     int ans = 0;
  28.     for (int r = 1; r <= n; r++) {
  29.         int l = lower_bound(minPref.begin(), minPref.end(), pref[r]) 
  30.                 - minPref.begin();
  31.         if (l > 0) {
  32.             ans = max(ans, r - pos[l - 1]);
  33.         }
  34.     }
  35.     return ans;
  36. }
  37.  
  38. int main() {
  39.     ios::sync_with_stdio(false);
  40.     cin.tie(nullptr);
  41.  
  42.     int n;
  43.     cin >> n;
  44.     string s;
  45.     cin >> s;
  46.  
  47.     int ans = 0;
  48.     ans = max(ans, solve_for('a', s));
  49.     ans = max(ans, solve_for('b', s));
  50.     ans = max(ans, solve_for('c', s));
  51.  
  52.     cout << ans << '\n';
  53. }
  54.  
Success #stdin #stdout 0s 5324KB
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stdin
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6
abcacc
stdout
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4
https://ideone.com/TI5Wv0
language:
C++14 (gcc 8.3)
created:
1 day ago
visibility:
public

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