C语言并查集的非递归实现详解

int find(int x) {
	int t=x;
	while(t!=pre[t]) t=pre[t];
	while(x!=pre[x]) {
		x=pre[x];
		pre[x]=t;
	}
	return t;
}
void merge(int x,int y) {
	if(find(x)!=find(y)) pre[find(x)]=find(y);
}

#include <iostream>
using namespace std;
const int maxn=1005;
int pre[maxn];
//int find(int x) {
//	if(x!=pre[x]) pre[x]=find(pre[x]);
//	return pre[x];
//}
int find(int x) {
	int t=x;
	while(t!=pre[t]) t=pre[t];
	while(x!=pre[x]) {
		x=pre[x];
		pre[x]=t;
	}
	return t;
}
void merge(int x,int y) {
	if(find(x)!=find(y)) pre[find(x)]=find(y);
}
int main() {
	int T,N,M;
	int p,q;
	scanf("%d",&T);
	while(T--) {
		int ans=0;
		scanf("%d%d",&N,&M);
		for(int i=1; i<=N; i++) pre[i]=i;
		for(int i=1; i<=M; i++) {
			scanf("%d%d",&p,&q);
			merge(p,q);
		}
		for(int i=1; i<=N; i++) {
			if(find(i)==i) ans++;
		}
		printf("%d\n",ans);
	}
	return 0;
}

int find(int x){
    int temp=x;
    while(temp!=d[temp])
        temp=d[temp];
    while(x!=d[x]){
        x=d[x];
        d[x]=temp;
    }
    return temp;
}