https://codeforces.com/contest/1741/problem/E
Let's introduce the dynamics. dp[i]=true if on the prefix ii the answer is Yes.

Then in this sequence b the numbers corresponding to the sizes of the segments from the partition a into subsegments will be called interesting.

A number at position i in the sequence b, if it is interesting, is either to the right or to the left of the segment.

  • If it is to the left of the segment, it can only be interesting if dp[i−1]=true. Then dp[i+b[i]]=true.
  • If it is on the right side of the segment, then if dp[i−b[i]−1]=true, then dp[i]=true.

The answer for the whole sequence is Yes if dp[n]=true.

#include <bits/stdc++.h>

using namespace std;

typedef long long ll, i64;

void slv() {
    int n;
    cin >> n;
    vector<int> b(n + 1), dp(n + 1, 0);
    dp[0] = 1;
    for (int i = 1; i <= n; i++) {
        cin >> b[i];
        if (dp[i - 1] == 1 && i + b[i] <= n) {
            dp[i + b[i]] = 1;
        }
        if (i - b[i] - 1 >= 0 && dp[i - b[i] - 1]) {
            dp[i] = 1;
        }
    }
    cout << (dp[n] == 1 ? "yes" : "no") << '\n';
}
signed main() {
    ios::sync_with_stdio(0), cin.tie(0);

    int t;
    cin >> t;
    while (t--) {
        slv();
    }
    return 0;
}