HDU 2122（最小生成树模板）

来源：互联网发布：断开连接的网络驱动器编辑：程序博客网时间：2024/06/18 05:48

题目地址：点击打开链接

思路：模板题，注意重边和不能构成的情况即可

AC代码：

#include <iostream>#include <cstdio>#include <cstdlib>#include <algorithm>#include <queue>#include <stack>#include <map>#include <cstring>#include <climits>#include <cmath>#include <cctype>typedef long long ll;using namespace std;const int zui = 1000000000;int n,m;int map1[1010][1010];int lowdist[1010];int visit[1010];int sum;bool flag;void Prim(){    int i,j,k;    sum = 0;    memset(visit,0,sizeof(visit));    for(i=0; i<=n-1; i++)    {        lowdist[i] = map1[0][i];    }    visit[0] = 1;    for(i=1; i<n; i++)    {        int min1 = zui;        k = -1;        for(j=0; j<=n-1; j++)        {            if(!visit[j] && lowdist[j] < min1)            {                min1 = lowdist[j];                k = j;            }        }        if(k == -1)        {            flag = false;            return;        }        visit[k] = 1;        sum += lowdist[k];        for(j=0; j<=n-1; j++)        {            if(!visit[j] && map1[k][j] < lowdist[j])            {                lowdist[j] = map1[k][j];            }        }    }}int main(){    int i,j;    while(scanf("%d%d",&n,&m) != EOF)    {        int a,b,c;        for(i=0; i<=n-1; i++)        {            for(j=0; j<=n-1; j++)            {                map1[i][j] = zui;            }        }        for(i=0; i<m; i++)        {            scanf("%d%d%d",&a,&b,&c);            if(c < map1[a][b])//注意重边            {                map1[a][b] = map1[b][a] = c;            }        }        flag = true;//注意这里刚开始是true        Prim();        if(flag)        {            printf("%d\n\n",sum);        }        else        {            printf("impossible\n\n");        }    }    return 0;}

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