HUD 1233 还是畅通工程

来源：互联网发布：华讯网络待遇怎么样编辑：程序博客网时间：2024/05/16 14:09

思想：简单最小生成树，kruskal。

#include<stdio.h>#include<algorithm>#include<iostream>#include<math.h>#include<string.h>#include<string>using namespace std;int per[105];int m;void init(){    for(int i = 0; i < 105; i ++)    {        per[i] = i;    }}struct Edge{    int x;    int y;    int dis;}edge[5005];bool cmp(Edge a, Edge b){    return a.dis < b.dis;}int find(int x){    int r = x;    while(r != per[r])        r = per[r];    int i = x;    int j;    while(i != r)    {        j = per[i];        per[i] = r;        i = j;    }    return r;}void join(int x, int y){    int s = find(x);    int e = find(y);    if(s != e)    {        per[s] = e;    }}int kruskal(int c){    sort(edge+1,edge+c+1,cmp);    int sum = 0,cnt = 0;    for(int i = 1; i <= c; i ++)    {        int s = find(edge[i].x);        int e = find(edge[i].y);        if(s != e)        {            join(s,e);            sum += edge[i].dis;            cnt++;        }        if(cnt == m-1)            break;    }    if(cnt < m-1)        return -1;    return sum;}int main(){    int n,a,b;    while(scanf("%d%d",&n,&m)!= EOF && n)    {        init();        int c = 0;        for(int i = 1; i <= n; i ++)        {            scanf("%d%d%d",&edge[i].x,&edge[i].y,&edge[i].dis);        }        int d = kruskal(n);        if(d == -1)        {            printf("?\n");            continue;        }        printf("%d\n",d);    }    return 0;}

如有错误，欢迎指出~

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