[AcWing 1016] 最大上升子序列和

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点击查看代码

#include<iostream>

using namespace std;

const int N = 1010;

int n;
int a[N], f[N];

int main()
{
	cin >> n;
	for (int i = 1; i <= n; i ++)	cin >> a[i];
	int res = 0;
	for (int i = 1; i <= n; i ++) {
		f[i] = a[i];
		for (int j = 1; j < i; j ++)
			if (a[i] > a[j])
				f[i] = max(f[i], f[j] + a[i]);
		res = max(res, f[i]);
	}
	cout << res << endl;
	return 0;
}

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1. 状态表示
   $f[i]$ 表示以 $a[i]$ 结尾的上升子序列和的最大值
2. 状态计算
   类比最大上升子序列模型，将计数改为和