HDOJ 2544 Dijkstra

迪杰斯特拉算法的过程如下：

初始化，把除起点之外的所有点到起点的距离初始化为 INF，起点到起点的距离记为0，标记清空，；

FOR i = 1:n

　　选取到起点距离最近的结点；

　　如果选取的点为目标点，结束，否则标记这个点，并对它相邻的所有点进行松弛操作；

END

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# include <stdio.h>

# include <string.h>



# define N 105

# define INF 100005



int n, m;

int w[N][N];



int min(int x, int y)

{

    return (x<y ? x:y);

}



void init(void)

{

    int i, j, u, v, t;

    

    for (i = 1; i <= n; ++i)

    for (j = 1; j <= n; ++j)

    {

        w[i][j] = INF;

    }



    for (i = 0; i < m; ++i)

    {

        scanf("%d%d%d", &u, &v, &t);

        if (t < w[u][v]) w[u][v] = w[v][u] = t;

    }

}



void solve(void)

{

    int d[N], i, m, x, j;

    char v[N];

    

    memset(v, 0, sizeof(v));

    for (d[1] = 0, i = 2; i <= n; ++i)

        d[i] = INF;

    for (i = 1; i <= n; ++i)

    {

        m = INF;

        for (j = 1; j <= n; ++j) if (!v[j] && d[j]<=m) m = d[x = j];

        if (x == n) break;

        v[x] = 1;

        for (j = 1; j <= n; ++j) d[j] = min(d[j], d[x]+w[x][j]);

    }

    printf("%d\n", d[n]);

}



int main()

{    

    while (scanf("%d%d", &n, &m), n&&m)

    {

        init();

        solve();

    }



    return 0;

}

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