poj1861-Network

题目链接 http://vjudge.net/problem/POJ-1861

解题思路

用Kruskal算法可以比较轻松地得到每次连接的边

但是我用了1000ms过的。。。（时限1000ms(⊙﹏⊙)b）可能是我写挫了吧

代码

#include<iostream>
#include<algorithm>
using namespace std;
const int MAX_SIZE = 1010;
const int INF = 1e9 + 7;
struct node {
  int x, y;
  int value;
}p[15010], edge[15010];
int father[MAX_SIZE];
int n, m;
int maxEdge;
void read()
{
  for(int i=0; i<m; i++) {
    cin >> p[i].x >> p[i].y >> p[i].value;
  }
}
void make()
{
  for(int i=1; i<=n; i++)
    father[i] = i;
}
int find(int x)
{
  if(x != father[x])
    father[x] = find(father[x]);
  return father[x];
}
bool cmp(node a, node b)
{
  if(a.x != b.x)
    return a.x < b.x;
  else if(a.y != b.y)
    return a.y < b.y;
}
bool cmp1(node a, node b)
{
    return a.value < b.value;
}
int kru()
{
  int cnt = 0;
  make();
  for(int i=0; i<m; i++) {
    int xf = find(p[i].x);
    int yf = find(p[i].y);
    if(xf == yf) continue;
    father[xf] = yf;
    if(p[i].value > maxEdge) maxEdge = p[i].value;
    edge[cnt].x = p[i].x;
    edge[cnt].y = p[i].y;
    cnt++;
  }
  return cnt;
}
int main()
{
  cin >> n >> m;
  read();
  sort(p, p+m, cmp1);
  int cnt = kru();
  //sort(edge, edge+cnt, cmp);
  cout << maxEdge << endl;
  cout << cnt << endl;
  for(int i=0; i<cnt; i++)
    cout << edge[i].x << " " << edge[i].y << endl;
  return 0;
}