POJ 1695 Magazine Delivery (三维坐标DP+逆推)

感觉这题上了些难度了。。第一次做三维DP。。。昨晚看完后睡了10个小时后想出来了。。。睡眠果然是精力集中的保障啊。。。还有这题倒着推很好写

状态转移方程：

　　　　dp[i][j][k]=min(dp[i+1][j][k]+map[i][i+1],dp[i+1][i][k]+map[j][i+1],dp[i+1][i][j]+map[k][i+1]);

//为避免混淆。。。数组还是从1开始搞起吧。。。

#include<stdio.h>
#include<string.h>
#define inf 100000000

int ncase;
int n;
int map[35][35];
int dp[35][35][35];

int min(int a, int b, int c)
{
	return (a<=b)?((a<=c)? a:c):((b<=c)? b:c);
}

int main()
{
	scanf("%d",&ncase);
	while (ncase--) {
		
		memset(dp, 0, sizeof(dp));
		
		scanf("%d",&n);
		
		for (int i=0; i<=n; i++)
			for (int j=0; j<=n; j++)
				map[i][j]=inf;
		
		for (int i=1; i<=n-1; i++)
			for (int j=i+1; j<=n; j++)
				scanf("%d",map[i]+j);
		
		for (int i=n-1; i>=1; i--) {
			for (int j=1; j<=i; j++) {
				for (int k=1; k<=j; k++) {
					dp[i][j][k]=min(dp[i+1][j][k]+map[i][i+1],dp[i+1][i][k]+map[j][i+1],dp[i+1][i][j]+map[k][i+1]);
				}
			}
		}
		
		printf("%d\n",dp[1][1][1]);
	}
}

啊