POJ1751--Highways（最小生成树，kauskal）

裸最小生成树。用kauskal做方便一些。

不得不说这么大数据用cin cout 真是作死。。活该T那么多次。。。

/*************************************************
Problem: 1751		User: G_lory
Memory: 4640K		Time: 594MS
Language: C++		Result: Accepted
*************************************************/
#include <iostream>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <cstring>

using namespace std;

const int MAXN = 755;
const int MAXM = MAXN * MAXN;

int par[MAXN];
int rk[MAXN];

struct Edge
{
    int u, v;
    double w;
    bool operator<(const Edge a) const
    {
        return w < a.w;
    }
} edge[MAXM];

int tol;

void addedge(int u, int v, double w)
{
    edge[tol].u = u;
    edge[tol].v = v;
    edge[tol++].w = w;
}

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

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 (rk[x] < rk[y]) par[x] = y;
    else par[y] = x;
    if (rk[x] == rk[y]) rk[x]++;
}

void Kruskal(int n, int m)
{
    sort(edge, edge + tol);
    int cnt = 0;
    for (int i = 0; i < tol; i++)
    {
        int t1 = find(edge[i].u);
        int t2 = find(edge[i].v);
        if (t1 != t2)
        {
            cout << edge[i].u << " " << edge[i].v << endl;
            unite(t1, t2);
            cnt++;
        }
        if (cnt == n - 1 - m) break;
    }
}

struct Point {
    double x, y;
    double dis(Point a)
    {
        return sqrt( (x - a.x) * (x - a.x) + (y - a.y) * (y - a.y) );
    }
} p[MAXN];

int main()
{
    int n, m;
    scanf("%d", &n);
    tol = 0;
    for (int i = 1; i <= n; ++i)
        scanf("%lf%lf", &p[i].x, &p[i].y);
    for (int i = 1; i <= n; ++i)
        for (int j = i + 1; j <= n; ++j)
            addedge(i, j, p[i].dis(p[j]));
    init(n);
    scanf("%d", &m);
    int a, b;
    int p = 0;
    for (int i = 0; i < m; ++i)
    {
        scanf("%d%d", &a, &b);
        if (find(a) != find(b))
        {
            unite(a, b);
            ++p;
        }
    }
    Kruskal(n, p);
    return 0;
}