2016夏季练习——最小生成树

来源：HDU1102

水题，但是并查集写了有问题会MLE

照着模板打的kruscal，还是太弱

#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;
int n;
int Q;
const int MAXN = 105;
struct Edge{
int u,v;
int w;
}edge[MAXN*MAXN];
int tol;
int fa[MAXN];
int ans;
bool cmp(Edge a,Edge b){
return a.w<b.w;
}
void addedge(int u,int v,int w){
edge[tol].u=u;
edge[tol].v=v;
edge[tol++].w=w;
}
int Find(int x){
if(fa[x]==x) return x;
else return fa[x]=Find(fa[x]);
}
void kruscal(){
sort(edge,edge+tol,cmp);
for(int i=0;i<tol;i++){
int x=edge[i].u;
int y=edge[i].v;
x=Find(x);
y=Find(y);
if(x!=y){
ans+=edge[i].w;
fa[y]=x;
}
}
}
int main(){
while(scanf("%d",&n)!=EOF){
tol=0;
int du;
memset(fa,0,sizeof(fa));
memset(edge,0,sizeof(edge));
for(int i=1;i<=n;i++){
for(int j=1;j<=n;j++){
scanf("%d",&du);
if(i>=j) continue;
addedge(i,j,du);
}
}
for(int i=1;i<=n;i++) fa[i]=i;
scanf("%d",&Q);
int x,y;
while(Q--){
scanf("%d%d",&x,&y);
x=Find(x);
y=Find(y);
fa[x]=y;
}
ans=0;
kruscal();
cout<<ans<<endl;
}
return 0;
}