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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. typedef long long ll;
  4. const int Mod=998244353;
  5.  
  6. void solve() {
  7.    int n;
  8.    cin >> n;
  9.    string s;
  10.    cin >> s;
  11.    if(n==1){
  12.     cout << ((s[0]=='1')?2:1) << '\n';
  13.     return;
  14.    }
  15.    int T01=0,T10=0;
  16.    int ans=(s[0]=='1')?2:1;
  17.  
  18.    for(int i=0;i<n-1;i++){
  19.     if(s[i]=='0' && s[i+1]=='1') T01++;
  20.     if(s[i]=='1' && s[i+1]=='0') T10++;
  21.    }
  22.  
  23.    int trans=T01+T10;
  24.  
  25.    int swap=0;
  26.    if(T01>=2 || T10>=2 || (s[0]=='1' && T01>=1))
  27.     swap=2;
  28.  
  29.    if(swap==0){
  30.      for(int i=0;i<n-1;i++){
  31.         if(s[i]!=s[i+1] && s[i]==s[n-1]){ 
  32.           swap=1;
  33.           break;}
  34.      }
  35.      if(s[0]=='1' && s[n-1]=='0') swap=1;
  36.    }
  37.    ans+=n+trans-swap;
  38.  
  39.    cout << ans-1 << '\n';
  40.  
  41. }
  42.  
  43. int main(){ 
  44.     ios::sync_with_stdio(false);
  45.     cin.tie(nullptr);
  46.  
  47.     int t;
  48.     cin >> t;
  49.     while (t--) solve();
  50.  
  51.  
  52.     return 0;
  53. }
  54.  
Success #stdin #stdout 0.01s 5288KB
comments (?)
stdin 
6
3
000
3
111
3
011
3
100
5
10101
19
1101010010011011100
stdout 
3
4
4
4
8
29
https://ideone.com/KQfmeL
language:
C++ (gcc 8.3)
created:
3 days ago
visibility:
public

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