最小生成树 Kruskual和Prim算法

最小生成树就是一个连通图的最小连通子集。

Kruskual算法：

hdu1223 code:

#include <iostream>
#include <cstdio>
#include<set>
#include<algorithm>
#include<cstring>
#include<cstdlib>
#define maxn 105
typedef long long ll;
using namespace std;
typedef struct roads{
    int s,e,dis;
}Roads;
int father[maxn];
int find(int x){
    if(x!=father[x])
        father[x]=find(father[x]);
    return father[x];
}
bool compare(Roads a,Roads b){
    return a.dis < b.dis;
}
Roads w[maxn*maxn];
int ans;
bool vis[maxn];
int main()
{
    int n;
    while(scanf("%d",&n)&&n!=0)
    {
        ans = 0;
        for(int i=0;i<=n;i++){
             father[i]=i;
         }
        for(int i = 0;i < (n*(n-1))/2 ;i ++)
        {
            scanf("%d %d %d",&w[i].s,&w[i].e,&w[i].dis);
        }
        sort(w,w+(n*(n-1))/2,compare);
        memset(vis,0,sizeof(vis));
        int cnt = 0;
        for(int i = 0;i < (n*(n-1))/2;i ++)
        {
            int x=find(w[i].s);
            int y=find(w[i].e);
            if(x!=y){
                ans+=w[i].dis;
                father[x]=y;
            }
        }
        printf("%d
",ans);
    }
    return 0;
}

prim算法：

hdu1102code：

#include <iostream>
#include <algorithm>
#include<queue>
#include<cstdio>
#include<cstring>
#include<list>
#define maxn 103
using namespace std;
typedef long long ll;
int dis[maxn];
int n;
vector<int> q;
int roads[maxn][maxn];
ll ans;
void prime(){
    for(int i = 1;i <= n;i ++)
    {
        q.push_back(i);
        dis[i] = roads[1][i];
    }
    while(q.size())
    {
        int t = 0;
        for(int i = 0;i < q.size();i ++){
            if(dis[q[t]] > dis[q[i]])
            {
                t = i;
            }
        }
        ans += dis[q[t]];
        for(int i = 0;i < q.size();i ++)
        {
            if(roads[q[t]][q[i]] < dis[q[i]]){
                dis[q[i]] = roads[q[t]][q[i]];
            }
        }
        int temp = q[t];
        q[t] = q[q.size() - 1];
        q[q.size()-1] = temp;
        q.pop_back();
    }
}
int main()
{
    int m,a,b,q1;

    while(scanf("%d",&n)!=EOF){
        q.clear();
        ans = 0;
        for(int i = 1;i <= n;i ++){
            for(int j = 1;j <= n;j ++){
                scanf("%d",&roads[i][j]);
            }
        }
        cin >> m;
        for(int i = 1;i <= m;i ++){
            scanf("%d %d",&a,&b);
            roads[a][b] = roads[b][a] = 0;
        }
        prime();
        printf("%d
",ans);
    }
    return 0;
}