HDU 2112 today(dij)

HDU Today

#include <stdio.h>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <map>
using namespace std;
#define inf 0x3f3f3f3f

int cast[205], vis[205], cnt;
int a[205][205];

void Dijkstra(int s,int e) {
    int i, j, min ,pos;
    memset(vis,0,sizeof(vis));

    for(i = s; i <= e; i++)
        cast[i] = (i == s ? 0 : inf);

    for(i = s; i <= e; i++) {
        min = inf;
        for(j = s; j <= e; j++) {
            if(cast[j] < min && !vis[j]) {
                pos = j;
                min = cast[j];
            }
        }

        vis[pos] = 1;
        if(min == inf)
            break;

        for(j = s; j <= e; j++) {
            if(cast[pos]+a[pos][j] < cast[j] && !vis[j])
                cast[j] = cast[pos]+a[pos][j];
        }
    }
}

int main() {
    //freopen("data.in", "r", stdin);
    map<string,int> mat;//在这里mat的作用是将字符串化为整数存储，然后进行dijkstra就可以解决问题
    char s1[100], s2[100];
    int i, cnt, flag,n,j;
    while(~scanf("%d",&n) && n>0) {
        mat.clear();
        memset(a, inf, sizeof(a));
        flag = 0;
        scanf("%s%s", s1, s2);
        if(!strcmp(s1, s2))
            flag = 1;

        mat[s1] = 1;
        mat[s2] = 2;
        cnt = 3;
        for(i = 0; i<n; i++) {
            int k;
            scanf("%s%s%d", s1, s2, &k);
            if(!mat[s1])
                mat[s1] = cnt++;

            if(!mat[s2])
                mat[s2] = cnt++;

            if(k < a[mat[s1]][mat[s2]])
                a[mat[s1]][mat[s2]] = a[mat[s2]][mat[s1]] = k;
        }

        if(flag) {
            printf("0\n");
            continue;
        }

        Dijkstra(1, cnt-1);

        printf("%d\n",cast[2] == inf ? -1: cast[2]);
    }

    return 0;
}