uva590 - Always on the run(简单动归)

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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 0x7fffffffint 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;}