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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. int f[100002][3], dp[100002][3];
  4. void solve() {
  5.     int n,m=0; cin >> n;
  6.     int a[n+1];
  7.     for(int i=1;i<=n;i++) {
  8.         cin >> a[i];
  9.         f[i][a[i]]=f[i-1][a[i]]+1;
  10.     }
  11.     for(int i=n;i>=1;i--) {
  12.         dp[i][a[i]]=dp[i+1][a[i]]+1;
  13.         m=max(m,min(f[i-1][1],dp[i][2]));
  14.         m=max(m,min(f[i-1][2],dp[i][1]));
  15.         m=max(m,min(f[i][1],dp[i+1][2]));
  16.         m=max(m,min(f[i][2],dp[i+1][1]));
  17.     }
  18.     cout << 2*m;
  19.     return;
  20. }
  21. int main() {
  22.     ios::sync_with_stdio(false);
  23.     cin.tie(0), cout.tie(0);
  24.     solve();
  25.     return 0;
  26. }
Success #stdin #stdout 0.01s 5284KB
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https://ideone.com/rV2jpE
language:
C++ (gcc 8.3)
created:
4 days ago
visibility:
public

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