(双向dp)acwing 1014. 登山

1014. 登山

题目链接https://www.acwing.com/problem/content/description/1016/
思路：之前看错题了，其实意思就是选一个点，然后往左右两边滑（每次只能选比上个点底的点），两边最长的加起来求最大值即可

#include<iostream>
#include<algorithm>
using namespace std;
int a[1100];
int main() {
    
    
	int n;
	cin >> n;
	for (int i = 1; i <= n; i++) {
    
    
		cin >> a[i];
	}
	int f[1100],g[1100];
	for (int i = n; i >= 1; i--) {
    
    
		f[i] = 1;//注意
		for (int j = n; j > i; j--) {
    
    
			if (a[i] > a[j])
				f[i] = max(f[i], f[j] + 1);
		}
		
	}
	for (int i = 1; i <=n; i++) {
    
    
		g[i] = 1;//注意
		for (int j = 1; j <i; j++) {
    
    
			if (a[i] > a[j])
				g[i] = max(g[i], g[j] + 1);
		}

	}
	int res = 0;
	for (int i = 1; i <= n; i++) {
    
    
		res = max(res, g[i] + f[i] - 1);
	}
	cout << res;
	return 0;

}