D - Challenging Valleys.cpp

#include <bits/stdc++.h>

using namespace std;

const int MX = 2e5 + 5;

int t, n, arr[MX];

int main(){
    cin.tie(nullptr), ios::sync_with_stdio(false);
    cin >> t;
    while(t--){
        cin >> n;
        for(int i = 0; i < n; i++) cin >> arr[i];
        int idx = min_element(arr, arr + n) - arr;
        bool ans = true;

        for(int i = idx - 1; i >= 0; i--){
            if(arr[i] < arr[i + 1]) ans = false;
        }

        for(int i = idx + 1; i < n; i++){
            if(arr[i] < arr[i - 1]) ans = false;
        }

        cout << (ans ? "YES\n" : "NO\n");
    }
}