SDNU 1224.Tom'problem B（迪杰斯特拉）

Description

Tom is a student in Shan Dong Normal University! his University in the suburbs,this day,Tom wanted to go to the downtown to visit his old friend Jerry,But tom faced a problem ,he want to know how to reach the city center fastest,now the bus stations of city are n[2,100], there are m[1,1000] bus routes in the city

Tom in the 1st bus station,Jerry in the Nth bus station

Input

The fist line is m,n;

Next m lines is a,b,c (a,b is the name of bus station , c is the time you cost from station a to station b)

Output

The shortest time tom reach city center

Sample Input

1 2
1 2 10
3 4
1 2 10
2 3 10
3 4 10

Sample Output

10
30

Source

Unknown

#include <cstdio>
#include <iostream>
#include <cmath>
#include <string>
#include <cstring>
#include <algorithm>
using namespace std;
#define ll long long
const int inf = 0x3f3f3f3f;
const int maxn = 1e3+8;
int n, m, cost[maxn][maxn], time[maxn];
bool sign[maxn];
void dij(int s)
{
    fill(time, time+n+1, inf);
    fill(sign, sign+n+1, 0);
    time[1] = 0;
    for(int i = 1; i <= n; i++)
    {
        int miao, ying = inf;
        for(int j = 1; j <= n; j++)
            if(!sign[j] && time[j] <= ying)
                ying = time[miao = j];
        sign[miao] = 1;
        for(int j = 1; j <= n; j++)
            if(time[j]>time[miao]+cost[miao][j])
                time[j] = time[miao]+cost[miao][j];
    }
}
int main()
{
    while(~scanf("%d%d", &m, &n) && (n+m))
    {
        for(int i = 1; i <= n; i++)
            for(int j = 1; j <= n; j++)
                cost[i][j] = inf;
        int a, b, c;
        while(m--)
        {
            scanf("%d%d%d", &a, &b, &c);
            if(cost[a][b]>c)
                cost[a][b] = cost[b][a] = c;
        }
        dij(1);
        printf("%d\n", time[n]);
    }
    return 0;
}