hdu1232畅通工程 并查集

#include<iostream>
#define maxn 1005
#define max(a,b) a>b?a:b
#define min(a,b) a<b?a:b
using namespace std;
int set[maxn];
int ifhas[maxn];
int s,e;
int n,m;
void init()
{
int i,j;
for(i = 1;i <= n;i ++){
set[i] = i;
ifhas[i] = 0;
}
}
void Merge(int a,int b)
{
int big,small;
big = max(set[a],set[b]);
small= min(set[a],set[b]);
for(int i = 1;i <= n;i ++)
{
if(set[i] == big){
set[i] = small;
}
}
}
int main(void)
{
while(cin >> n && n!=0)
{
init();
cin >> m;
int i,j;
for(i = 0;i < m;i ++){
cin >> s >> e;
Merge(s,e);
}
int ans = 0;
for(int i = 1;i <= n;i ++)
{
if(ifhas[set[i]] == 0){
ans ++;
ifhas[set[i]] = 1;
}
}
cout << ans - 1 << endl;
}
return 0;
}

#include <iostream>
#include <algorithm>
#define maxn 1005
using namespace std;
int set[maxn];void init(int n)
{
int i;
for(i = 1;i <=n;i ++)
{
set[i] = i;
}
}
int find(int x)
{
int fa = x;
while(fa != set[fa])
fa = set[fa];
return fa;
}
void merge(int a,int b)
{
int fa,fb;
fa = find(a);
fb = find(b);
set[fb] = fa;
}
int main()
{
int n,m,a,b;

while(cin >> n && n!= 0)
{
init(n);
cin >> m;
for(int i = 1;i <= m;i ++){
cin >> a >> b;
merge(a,b);
}
for(int i = 1;i <= n;i ++){
set[i] = find(i);
//cout << "set[" << i << "]=" << set[i] << endl;
}
int ans = 0;
for(int i = 1;i <= n;i ++)
{
if(set[i] == i){
ans ++;
}
}
cout << ans - 1 << endl;
}
return 0;
}

#include <iostream>
#include <algorithm>
#define maxn 1005
using namespace std;
int set[maxn];
int height[maxn];
void init(int n)
{
int i;
for(i = 1;i <=n;i ++)
{
set[i] = i;
height[i] = 1;
}
}
int find(int x)
{
int fa = x;
while(fa != set[fa])
fa = set[fa];
return fa;
}
void merge(int a,int b)
{
int fa,fb;
fa = find(a);
fb = find(b);
if(height[fa] > height[fb]){
set[fb] = fa;
}
else if(height[fb] > height[fa]){
set[fa] = fb;
}
else{
set[fb] = fa;
height[fa] ++;
}
}
int main()
{
int n,m,a,b;

while(cin >> n && n!= 0)
{
init(n);
cin >> m;
for(int i = 1;i <= m;i ++){
cin >> a >> b;
merge(a,b);
}
for(int i = 1;i <= n;i ++){
set[i] = find(i);
//cout << "set[" << i << "]=" << set[i] << endl;
}
int ans = 0;
for(int i = 1;i <= n;i ++)
{
if(set[i] == i){
ans ++;
}
}
cout << ans - 1 << endl;
}
return 0;
}

#include <iostream>
#include <algorithm>
#define maxn 1005
using namespace std;
int set[maxn];
int height[maxn];
void init(int n)
{
int i;
for(i = 1;i <=n;i ++)
{
set[i] = i;
height[i] = 1;
}
}
int find(int x)
{
int fa = x;
int j,i;
while(fa != set[fa])
fa = set[fa];
i = x;
while(i != fa)
{
j = set[i];
set[j] = fa;
i = j;
}
return fa;
}
void merge(int a,int b)
{
int fa,fb;
fa = find(a);
fb = find(b);
if(height[fa] > height[fb]){
set[fb] = fa;
}
else if(height[fb] > height[fa]){
set[fa] = fb;
}
else{
set[fb] = fa;
height[fa] ++;
}
}
int main()
{
int n,m,a,b;

while(cin >> n && n!= 0)
{
init(n);
cin >> m;
for(int i = 1;i <= m;i ++){
cin >> a >> b;
merge(a,b);
}
for(int i = 1;i <= n;i ++){
set[i] = find(i);
//cout << "set[" << i << "]=" << set[i] << endl;
}
int ans = 0;
for(int i = 1;i <= n;i ++)
{
if(set[i] == i){
ans ++;
}
}
cout << ans - 1 << endl;
}
return 0;
}