Poj1287--Networking(最小生成树)

最新推荐文章于 2022-02-25 15:43:19 发布

转载最新推荐文章于 2022-02-25 15:43:19 发布 · 68 阅读

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原文链接：http://www.cnblogs.com/soTired/p/4837793.html

本文详细解析了POJ在线编程平台上的最小生成树模版题，通过使用C++实现Prim算法解决该问题，包括初始化、查找父节点、合并集合等关键步骤，并通过实例演示算法的具体应用。

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题目：http://poj.org/problem?id=1287

题目不多说，最小生成树模版题。

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
struct NoThing
{
    int from, to, val;
} edge[10001];
bool cMp(NoThing from, NoThing to)
{
    return from.val < to.val;    
} 
int n, m, father[51];
void init()
{
    for(int i = 1; i <= n; i++)
        father[i] = i;
}
int Find(int a)
{
    if(a == father[a])
        return a;
    else
        return father[a] = Find(father[a]); 
}
bool Mercy(int a, int b)
{
    int Q = Find(a);
    int P = Find(b);
    if(Q != P)
    {
        father[Q] = P;
        return true;        
    }    
    return false;
}
int main()
{
    while(~scanf("%d", &n), n)
    {
        init();
        scanf("%d", &m);
        for(int i = 0; i < m; i++)
            scanf("%d%d%d", &edge[i].from, &edge[i].to, &edge[i].val);
        sort(edge, edge+m, cMp);
        int sum = 0;
        for(int i = 0; i < m; i++)
            if(Mercy(edge[i].from, edge[i].to))
                sum += edge[i].val;
        printf("%d\n", sum); 
    }
    return 0;
}

#include <cstdio>
#include <cstring>
#include <iostream>
#define M 51 
using namespace std;
const int INF = 0x3f3f3f3f;
int n, m, vis[M], dis[M], map[M][M]; 
void Prime()
{
    int sum = 0;
    memset(vis, 0, sizeof(vis));
    for(int i = 1; i <= n; i++)
        dis[i] = map[1][i];
    vis[1] = 1;
    for(int i = 1; i < n; i++)
    {
        int temp = 1, min = INF;
        for(int j = 1; j <= n; j++)
        {
            if(!vis[j] && dis[j] < min)
            {
                temp = j;
                min = dis[j];    
            }    
        } 
        if(min == INF)
            return;
        vis[temp] = 1;
        sum += min;
        for(int j = 1; j <= n; j++)
            if(!vis[j] && dis[j] > map[temp][j])
                dis[j] = map[temp][j];
    }
    printf("%d\n", sum);
} 
int main()
{
    while(~scanf("%d", &n), n)
    {
        scanf("%d", &m);
        for(int i = 1; i <= n; i++)
            for(int j = 1; j <= n; j++)
            {
                if(i == j)
                    map[i][j] = 0;
                else
                    map[i][j] = INF;
            }
        for(int i = 0; i < m; i++)
        {
            int a, b, c;
            scanf("%d%d%d", &a, &b, &c);
            if(map[a][b] > c)
                map[a][b] = map[b][a] = c;
        }
        Prime();
    }
    return 0;
}