hdu1233 还是畅通工程 基础最小生成树

//克鲁斯卡尔
#include<iostream>
#include<algorithm>
using namespace std;
const int maxn = 10005;
struct node
{
    int begin, end, len;
}cun[maxn];
int n, fa[maxn], ans, m;

bool cmp(node a, node b)
{
    return a.len<b.len;  //按长度有小到大排序 
}

void init()
{
    for (int i = 0; i <= n; i++)
    {
        fa[i] = i;
    }
}

int find(int x)
{
    if (x == fa[x])
        return fa[x];
    else
        return fa[x] = find(fa[x]);
}

void join(int a, int b)
{
    a = find(a);
    b = find(b);
    if (a != b)
        fa[b] = a;
}

int kruskal()
{
    sort(cun, cun + m, cmp);
    init();  //初始化并查集 
    ans = 0;
    for (int i = 0; i<m; i++)
    {
        if (find(cun[i].begin) != find(cun[i].end)) //一条边的两个端点不在同一个集合，则选他，并合并 
        {
            join(cun[i].begin, cun[i].end);
            ans += cun[i].len;
        }
    }
    return ans;
}

int main()
{
    while (cin >> n)
    {
        if (n == 0) break;
        m = n*(n - 1) / 2;
        for (int i = 0; i<m; i++)
            cin >> cun[i].begin >> cun[i].end >> cun[i].len;
        cout << kruskal() << endl;
    }
    return 0;
}

//prim
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
using namespace std;

#define INF 0x7fffffff
# define MAXN 120
typedef long long int LL;

LL n, m;
LL cmpa[MAXN][MAXN], book[MAXN], dis[MAXN];

int main()
{
    LL a, b, weight, ans, p, q, f1, f2, minn, mark;
    while (scanf("%I64d", &n) && n)
    {
        //初始化 这题prime算法合适，边那摩多，都是完全图了
        for (LL i = 0; i<MAXN; i++)
        {
            dis[i] = INF;
            for (LL j = 0; j<MAXN; ++j)
                cmpa[i][j] = INF;
        }

        memset(book, 0, sizeof(book));
        ans = 0;

        for (LL i = 0; i<n*(n - 1) / 2; ++i)
        {
            scanf("%I64d %I64d %I64d", &a, &b, &weight);
            cmpa[a][b] = cmpa[b][a] = weight;
        }

        //连通图
        book[1] = 1;
        dis[1] = -1;

        for (LL t = 1; t<n; ++t)
        {
            for (LL i = 2; i <= n; ++i)
            {//更新dis中的值 
                for (LL j = 1; j <= n; ++j)
                {
                    if (book[j] && dis[i]>cmpa[i][j])
                    {  //j在树中 
                        dis[i] = cmpa[i][j];
                    }
                }
            }

            //选点建树
            minn = INF, mark = 0;
            for (LL i = 2; i <= n; ++i)
            {
                if (book[i])
                    continue;
                else
                {
                    if (dis[i] < minn)
                    {
                        minn = dis[i];
                        mark = i;
                        }
                }
            }

            if (minn != INF)
            {
                ans += minn;
                book[mark] = 1;
                dis[mark] = -1;
            }
                    
        }
        cout << ans << endl;

    }
    return 0;
}