1848F - Vika and Wiki - CodeForces Solution

#include <bits/stdc++.h>
using namespace std;
#define pb push_back
// #define int long long
// #define ll long long int
int INF = 2e18;
int n;
int check(vector<int> v, int k){
    for (int b=19; b>=0; b--) if ((k>>b)&1) {
        int bp = (1<<b);
        vector<int> w = v;
        for (int i=0; i<n; i++) w[i] = v[i]^v[(i+bp)%n];
        v = w;
    }
    vector<int> Z(n, 0);
    return v == Z;
}
void solve(){
    cin >> n;
    vector<int> v(n);
    vector<int> Z(n, 0);
    for (int i=0; i<n; i++) cin >> v[i];
    if (v==Z){
        cout << "0\n";return;
    }
    int low = 0; int high = n;
    // cout << check(v, 2ll) << "\n";
    while (high-low>1){
        int mid = (low+high)/2;
        if (check(v, mid)) high = mid;
        else low = mid;
    }
    cout << high << "\n";
}
int32_t main(){
    ios_base::sync_with_stdio(0);
    cin.tie(nullptr);
	// inv_init(1e6);
    int t; t=1;
    // cin >> t;
    for (int i=0; i<t; i++) solve();
}