[ZOJ 4024] Peak

题目链接：http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=4024

从前往后找满足al<al+1的最大下标l，从后往前找满足ar−1>ar的最小下标r，如果l=r且1<l<n则满足条件

#include <iostream>
#include <cstdio>

using namespace std;

const int maxn = 100005;

int arr[maxn];

int t, n;

int main() {
    scanf("%d", &t);
    while (t--) {
        scanf("%d", &n);
        for (int i = 0; i < n; i++) {
            scanf("%d", &arr[i]);
        }
        int l, r;
        for (int i = 0; i < n - 1; i++) {
            if (arr[i] >= arr[i + 1]) {
                l = i;
                break;
            }
        }
        for (int i = n - 1; i >= l; i--) {
            if (arr[i - 1] <= arr[i]) {
                r = i;
                break;
            }
        }
        if (l == r && 0 < l && l < n - 1) {
            printf("Yes\n");
        } else {
            printf("No\n");
        }
    }
}