poj2395 Out of Hay

思路：

MST
实现：

#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <cmath>
using namespace std;

struct edge
{
    int a, b, cost;
};
edge es[10005];
int ran[2005];
int par[2005];
int n, m, x, y, c;

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

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

void unite(int x, int y)
{
    x = find(x);
    y = find(y);
    if (x == y)
        return;
    if (ran[x] < ran[y])
    {
        par[x] = y;
    }
    else
    {
        par[y] = x;
        if (ran[x] == ran[y])
        {
            ran[x] ++;
        }
    }
}

bool same(int x, int y)
{
    return find(x) == find(y);
}

bool cmp(const edge & a, const edge & b)
{
    return a.cost < b.cost;
}

int kru()
{
    init(n);
    sort(es, es + m, cmp);
    int maxn = 0;
    for (int i = 0; i < m; i++)
    {
        if (!same(es[i].a, es[i].b))
        {
            unite(es[i].a, es[i].b);
            maxn = max(maxn, es[i].cost);
        }
    }
    return maxn;
}

int main()
{
    scanf("%d %d", &n, &m);
    for (int i = 0; i < m; i++)
    {
        scanf("%d %d %d", &x, &y, &c);
        es[i].a = x;
        es[i].b = y;
        es[i].cost = c;
    }
    int tmp = kru();
    printf("%d
", tmp);
    return 0;
}