Codeforces Round #424 (Div. 2, rated, based on VK Cup Finals) 简单暴力

看清题意

除了中间的峰顶，两边的数列 必须是严格上升下降的，只要记录最大值两边扫一遍就是了

#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <queue>
#include <vector>
#include <set>
#include <stack>
#include <map>
#include <climits>

using namespace std;

typedef long long ll;
const int maxn = 100 + 7, INF = 0x3f3f3f3f, mod = 1e9 + 7;

int n;
int a[maxn];

int main() {
scanf("%d", &n);
int max_ = 0, id = -1;
for(int i = 0; i < n; ++i) {
scanf("%d", &a[i]);
if(a[i] > max_) { max_ = a[i]; id = i; }
}
int j = id-1;
while(a[j] == a[j+1] && j >= 0) j--;
for(; j >= 0; --j) {
if(a[j] >= a[j+1]) return 0*puts("NO");
}
j = id+1;
while(a[j] == a[j-1] && j < n) j++;
for(; j < n; ++j)
if(a[j] >= a[j-1]) return 0*puts("NO");
puts("YES");
return 0;
}