Envío 2485

Código

#include <bits/stdc++.h>

using namespace std;

#define endl '\n'
#define ll long long
#define pii pair<int, int>
const int maxi = 1e6;
vector<int>kmp(maxi);

int main(){
  ios::sync_with_stdio(0); cin.tie(0); 
  string s; cin>>s;
  int ans = 0;
  for(int i=1;i<s.size();i++){
    int j = kmp[i-1];
    while(j>0 && s[i] != s[j]){
      j= kmp[j-1];
    }
    if(s[i] == s[j]){
      j++;
    }
 //   ans = max(ans, j);
    kmp[i] = j;
  }
//  cout<<ans<<endl;
  cout<<kmp[s.size()-1]<<endl;
  
  return 0;
}