HDU 1546 Idiomatic Phrases Game（最短路径）DIJ算法

Idiomatic Phrases Game

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 3144    Accepted Submission(s): 1019

Problem Description

Tom is playing a game called Idiomatic Phrases Game. An idiom consists of several Chinese characters and has a certain meaning. This game will give Tom two idioms. He should build a list of idioms and the list starts and ends with the two given idioms. For every two adjacent idioms, the last Chinese character of the former idiom should be the same as the first character of the latter one. For each time, Tom has a dictionary that he must pick idioms from and each idiom in the dictionary has a value indicates how long Tom will take to find the next proper idiom in the final list. Now you are asked to write a program to compute the shortest time Tom will take by giving you the idiom dictionary. 

 

Input

The input consists of several test cases. Each test case contains an idiom dictionary. The dictionary is started by an integer N (0 < N < 1000) in one line. The following is N lines. Each line contains an integer T (the time Tom will take to work out) and an idiom. One idiom consists of several Chinese characters (at least 3) and one Chinese character consists of four hex digit (i.e., 0 to 9 and A to F). Note that the first and last idioms in the dictionary are the source and target idioms in the game. The input ends up with a case that N = 0. Do not process this case. 

 

Output

One line for each case. Output an integer indicating the shortest time Tome will take. If the list can not be built, please output -1.

 

Sample Input

55 12345978ABCD23415 23415608ACBD34127 34125678AEFD412315 23415673ACC341234 41235673FBCD2156220 12345678ABCD30 DCBF5432167D0

 

Sample Output

17-1

 

Author

ZHOU, Ran

 

Source

Zhejiang Provincial Programming Contest 2006

题意：给出一定数目的节点，每个节点的信息用给出的字符串来表示。如果A字符串的最后4个字符是B字符串开头4个字符，类似B符合A成语接龙的条件，就认为A 到B 是连通的（有向的），这条边的权值是A字符串前面的数字，这个数字代表从A成语到B成语需要的拼写时间，问从第一个成语接到最后一个成语需要的最短时间。

#include<stdio.h>#include<string.h>#include<algorithm>using namespace std;const int maxm=1e3+10;const int inf=1<<29;char s[maxm][maxm];int v[maxm];int w[maxm][maxm];int vis[maxm];int d[maxm];int n;void dij(){    for(int i=1;i<=n;i++)    {        d[i]=w[1][i];        vis[i]=0;    }    d[1]=0;    vis[1]=1;    for(int i=1;i<=n;i++)    {        int now=inf,k=1;        for(int j=1;j<=n;j++)        {            if(!vis[j]&&now>d[j])            {                now=d[j];                k=j;            }        }        vis[k]=1;        for(int j=1;j<=n;j++)        {            if(!vis[j]&&d[j]>d[k]+w[k][j])            {                d[j]=d[k]+w[k][j];            }        }    }    if(d[n]==inf)        printf("-1\n");    else        printf("%d\n",d[n]);}int main(){    while(scanf("%d",&n)!=EOF&&n)    {        for(int i=1;i<=n;i++)        {            scanf("%d%s",&v[i],s[i]);        }        for(int i=1;i<=n;i++)        {            int len=strlen(s[i]);            for(int j=1;j<=n;j++)            {                if(s[j][0]==s[i][len-4]&&s[j][1]==s[i][len-3]&&s[j][2]==s[i][len-2]&&s[j][3]==s[i][len-1])                    w[i][j]=v[i];                else                     w[i][j]=inf;            }        }        dij();    }    return 0;}