uva590 - Always on the run(简单动归)

状态：dp[i][j]表示第i天到达j号城市的最小花费

状态转移：dp[i][j] = min(dp[i-1][k]);

注意边界是dp[0][1] = 0,而不是dp[1][1] = 0;

代码如下：

#include <cstdio>
#include <cstring>
#define N 15
#define K 1005
#define INF 0x7fffffff
int n, k, d, dp[K][N], a[N][N][K];
int main ()
{
    int tt = 0;
    while(scanf("%d %d",&n,&k),n+k)
    {
        for(int i = 1; i <= n; i++) for(int j = 1; j <= n; j++)
        {
            if(i==j) continue;
            scanf("%d",&d);
            a[i][j][0] = d;
            for(int l = 1; l <= d; l++) scanf("%d",&a[i][j][l]);
        }
        memset(dp,-1,sizeof(dp));
        dp[0][1] = 0;
        for(int i = 1; i <= k; i++)
        {
            for(int j = 1; j <= n; j++)
            {
                int &ans = dp[i][j];
                ans = INF;
                for(int l = 1; l <= n; l++)
                {
                    if(l==j) continue;
                    if(dp[i-1][l]==-1) continue;
                    int num = i%a[l][j][0];
                    if(num==0) num = a[l][j][0];
                    int value = a[l][j][num];
                    if(value==0) continue;
                    ans = ans<dp[i-1][l]+value?ans:dp[i-1][l]+value;
                }
                if(ans==INF) ans = -1;
            }
        }
        printf("Scenario #%d\n",++tt);
        if(dp[k][n]==-1) printf("No flight possible.\n\n");
        else printf("The best flight costs %d.\n\n",dp[k][n]);
    }
    return 0;
}