1807C - Find and Replace - CodeForces Solution

#include<iostream>
#include<queue>
#include<stack>
#include<deque>
#include<algorithm>
#include<vector>
#include<cmath>
#include<string>
#include<iomanip>
#include<map>
#include<set>
#include<bitset>
#define ll long long
#define T int t;  cin>>t; while(t--)
#define pb  push_back
#define vv vector
#define ss string
#define so(vec) sort(vec.begin(), vec.end())
#define srt(vec) sort(vec.rbegin(), vec.rend())
#define s(s) sort(s.begin(), s.end())
#define all(vec) vec.begin(), vec.end()
#define sor(arr,n) sort(arr, arr+n)
#define yes cout<<"YES\n"
#define no cout<<"NO\n"
#define  Mod 10000000007
const double PI = 3.14159265358979323846;
using namespace std;
void  HaiDO0da() {
    ios_base::sync_with_stdio(false);
    cout.tie(NULL);
    cin.tie(NULL);
}

int main()
{
     /////////////////////// Kendeine inan ve hep mutlu ol//////////////////////////////
  HaiDO0da();
   // freopen("hello.in", "r", stdin);
   T{
       int n,f=1; cin>>n;
       ss x;  cin>>x;
        vector<pair<char, int>>vec(130);
        for (int i = 0; i < n; i++) {
            if (vec[x[i]].second == 0) {
                if (i % 2 == 0) {
                    vec[x[i]].second = 1;
                }
                else
                    vec[x[i]].second = 2;
            }
        }
        for (int i = 1; i < n; i++) {
            if (vec[x[i]].second == vec[x[i-1]].second) {
                f = false;
                break;
            }
        }
        if (f) yes;
        else no;
    }
}