蓝桥杯 历年试题 国王的烦恼

题目分析

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int maxn = 1e4+10;
const int maxm = 1e5+100;
const int INF = 0x3f3f3f3f;

struct Edge{
int from, to, val;
Edge(){}
Edge(int a, int b, int c):from(a), to(b), val(c){}
bool operator < (const Edge e)const{
return  val > e.val;
}
};

Edge e[maxm];
int fa[maxn];

int Find(int x){
return  fa[x] == x?fa[x]:fa[x] = Find(fa[x]);
}

int main(){
int n, m;
while(scanf("%d%d", &n, &m) != EOF){
for(int i = 0; i < maxn; i++) fa[i] = i;
int from, to, val;
for(int i = 0; i < m; i++){
scanf("%d%d%d", &from, &to, &val);
e[i] = Edge(from, to, val);
}
sort(e, e+m);
int ans = 0, temp = INF;
for(int i = 0; i < m; i++){
int xx = Find(e[i].from);
int yy = Find(e[i].to);
if(xx != yy){
fa[xx] = yy;
if(e[i].val < temp){
temp = e[i].val;
ans++;
}
}
}
printf("%d\n", ans);
}
return 0;
}