题目描述
blablabla
C++ 代码
#include<bits/stdc++.h>
#define endl '\n'
#define debug(a) cout<<#a<<"="<<a<<endl;
#define fast ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
#define x first
#define y second
#define mm memset
#define int long long
using namespace std;
typedef long long LL;
typedef pair<int,int> PII;
int n;
char p[26];
void solve(){
cin >> n;
string s;
cin >> s;
for(int i = 0; i < 26; i ++) p[i] = '?';
for(int i = 0; i < n; i ++){
if(p[s[i] - 'a'] == '?') p[s[i] - 'a'] = i % 2 + '0';
else if(p[s[i] - 'a'] != '0' + i % 2){
cout << "NO" << endl;
return ;
}
}
cout << "YES" << endl;
}
signed main(){
fast
int T;
//T = 1;
cin >> T;
while(T --) solve();
return 0;
}