poj 1976 A Mini Locomotive 动规

       这题有些像求连续子序列和的最大值

       设dp[i][j]表示i个火车头拉动j个火车舱的人数和的最大值，状态方程如下：dp[i][j] = max(dp[i-1][j-times]+num[j]+..+num[j-times+1], dp[i][k])

 

#include <iostream>

#include <cstdio>

#include <cstring>

using namespace std;



const int MAX = 50005;



int dp[5][MAX];

int num[MAX];

int n;



int main()

{

	int cases;



	scanf("%d", &cases);

	int times;



	while (cases--)

	{

		scanf("%d", &n);

		for (int i = 1; i <= n; i++)

			scanf("%d", &num[i]);



		scanf("%d", &times);

		memset(dp, 0, sizeof(dp));



		for (int i = 1; i <= 3; i++)

			for (int v = times; v <= n; v++)

			{

				int sum = 0;

				for (int j = 0; j < times; j++)

					sum += num[v-j];

				dp[i][v] = dp[i-1][v-times] + sum;

				for (int k = i*times; k < v; k++)

					dp[i][v] = max(dp[i][v], dp[i][k]);

			}



		printf("%d\n", dp[3][n]);

	}

	return 0;

}