UVa 1025 - A Spy in the Metro（白书）

来源：互联网发布：在线分配算法编辑：程序博客网时间：2024/06/05 11:41

题目地址：https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=245&page=show_problem&problem=3466

思路：我写的是填表法，书上写的是刷表法，刚开始因为一个数组叫time，re了好几发

AC代码：

#include <iostream>#include <cstdio>#include <cstdlib>#include <algorithm>#include <queue>#include <stack>#include <map>#include <cstring>#include <climits>#include <cmath>#include <cctype>const int inf = 0x3f3f3f3f;//1061109567typedef long long LL;#define lson l,m,rt<<1#define rson m+1,r,rt<<1|1using namespace std;int time1[55];int train[210][55][2];//0表示往右开有车，1表示往左开有车int dp[210][55];//表示在时刻i，火车在车站j的所用的最短时间int main(){    int n,t;    int cas = 1;    while(scanf("%d",&n) && n)    {        memset(train,0,sizeof(train));        memset(dp,inf,sizeof(dp));        scanf("%d",&t);        for(int i=1; i<n; i++)            scanf("%d",&time1[i]);        int d,m1,m2;        scanf("%d",&m1);        while(m1--)//往右开        {            scanf("%d",&d);            for(int j=1; j<n; j++)            {                if(d <= t)                    train[d][j][0] = 1;                d += time1[j];            }        }        scanf("%d",&m2);        while(m2--)        {            scanf("%d",&d);            for(int j=n; j>=2; j--)            {                if(d <= t)                    train[d][j][1] = 1;                d += time1[j-1];            }        }        dp[0][1] = 0;        for(int i=0; i<=t; i++)        {            for(int j=1; j<=n; j++)            {                dp[i+1][j] = min(dp[i+1][j],dp[i][j]+1);//等待一秒                if(train[i][j][0] && j < n && i + time1[j] <= t)//往右走                    dp[i+time1[j]][j+1] = min(dp[i+time1[j]][j+1],dp[i][j]);                if(train[i][j][1] && j > 1 && i + time1[j-1] <= t)//往左走                    dp[i+time1[j-1]][j-1] = min(dp[i+time1[j-1]][j-1],dp[i][j]);            }        }        if(dp[t][n] == inf)            printf("Case Number %d: impossible\n",cas++);        else            printf("Case Number %d: %d\n",cas++,dp[t][n]);    }    return 0;}

0 0