poj 2387 Til the Cows Come Home

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最基本的最短路问题

#include <iostream>#include <cstdio>#include <algorithm>#include <cstring>using namespace std;const int INF = 0x3f3f3f3f;int edge[2005][2005];int main(){    int n, k;    cin >> k >> n;    int v, u, dis;    for (int i = 0; i != n; ++i)        for (int j = 0; j != n; ++j)            edge[i][j] = INF;    for (int i = 0; i != k; ++i)  // 无向图 建立双向边    {        scanf("%d%d%d",&v,&u,&dis);        if (edge[v-1][u-1] >= dis)        edge[v-1][u-1] = dis;        if (edge[u-1][v-1] >= dis)        edge[u-1][v-1] = dis;    }    int vis[2005],d[2005];    memset(d,0,sizeof(d));    memset(vis,0,sizeof(vis));    for (int i = 1; i != n; ++i)        d[i] = INF;    for (int i = 0; i != n; ++i)    {        int point;        int minn = INF;        for (int j = 0; j != n; ++j)            if (!vis[j] && d[j] < minn)                {                    minn = d[j];                    point = j;                }        vis[point] = 1;        for (int j = 0; j != n; ++j)            if (!vis[j])            d[j] = min(d[j],d[point] + edge[point][j]); //*松弛    }    cout << d[n-1] << endl;    return 0;}

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