uva 1025 A Spy in the Metro dp状态转移

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

#define INF 100000000
using namespace std;

int n,T,m1,m2;

int t[100];
int A1[100];
int A2[100];
int B1[100][100];
int B2[100][100];
int dp[300][100];

int find(int key,int *a,int len){
	int ma = -1;

	for(int i = 0;i < len;i++){
		if(a[i] <= key && a[i] > ma){
			ma = a[i];
		}
	}
	return ma;
}
int main(){
	int q = 1;

	while(cin >> n,n){
		scanf("%d",&T);

		for(int i = 1;i < n;i++){
			scanf("%d",&t[i]);
		}
		scanf("%d",&m1);
		for(int i = 0;i < m1;i++){
			scanf("%d",&A1[i]);
			B1[1][i] = A1[i]; 

		}

		scanf("%d",&m2);
		for(int i = 0;i < m2;i++){
			scanf("%d",&A2[i]);
			B2[n][i] = A2[i];
		}

		for(int i = 2 ;i <= n;i++){
			for(int j = 0;j < m1;j++){
				B1[i][j] = B1[i-1][j] + t[i-1];
			}
		}

		for(int i = n-1;i >= 1;i--){
			for(int j = 0;j < m2;j++){
				B2[i][j] = B2[i+1][j] + t[i];
			}
		}

		for(int i = 0;i <= T;i ++){
			for(int j = 0;j <= n;j++ ){
					dp[i][j] = INF;
			}
		}
		//dp[i][j]的意思是第i时刻到达j站点的最小时间，只有三种状态能到达该状态
		//1 原先就在这个位置然后再多等了1分钟 ，dp[i][j] = dp[i-1][j]
		//2 从他前一个站点到达然后开始等待,dp[i][j] = dp[x-t[j-1]][j-1] + i - x;
		//3 从他后一个站点到达然后才开始等待,dp[i][j] = dp[y-t[j]][j+1] + i - y;
		//取这三种之间最小的那个就是这个最小的时间了
		dp[0][1] = 0;
		for(int i = 1;i <= T;i++){
			for(int j = 1;j <= n;j++){
				int  a,c,d;
				a = dp[i-1][j] + 1;
				int x = find(i,B1[j],m1);
				int y = find(i,B2[j],m2);
				if(x < 0){
					c = INF;
				}
				else{
					if((j-1)> 0)
					c = dp[x-t[j-1]][j-1]+i-x;
					else
					c = INF;
				}
				if(y<0){
					d = INF;
				}
				else{
					if((j+1) <= n)
						d = dp[y-t[j]][j+1]+i-y;
					else
						d = INF;
				}
				dp[i][j] = min(a,min(c,d));
			}
		}

		if(dp[T][n] != INF)
			printf("Case Number %d: %d\n",q++,dp[T][n]);
		else
			printf("Case Number %d: impossible\n",q++);
	}
	return 0;
}