POJ 1611 The Suspects 解題報告

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簡單的並查集題目，合併一個團隊的人即可。

AC code solution1

#include<iostream>
#include<queue>
#include<cstring>
#include<string>
#include<sstream>
#include<map>
#include<vector>
#include<cstdio>
#include<iostream>
#include<cmath>
#include<algorithm>
#include<cstdlib>
#include<stack>
#include<ctime>
using namespace std; 
#define rep(i,aa,bb) for(register int i=aa;i<=bb;i++)
#define rrep(i,aa,bb) for(register int i=aa;i>=bb;i--)
#define mset(var,val)	 memset(var,val,sizeof(var))
#define LL long long 
#define eps 0.000001
#define inf 0x7f7f7f7f
#define llinf 1e18
#define exp 0.000001
#define pai 3.141592654
#define random(x)   rand()%(x)
#define lowbit(x)   x&(-x)
inline int read()
{
	int x=0,y=1;char a=getchar();while ( a>'9' || a<'0'){if ( a=='-')y=-1;a=getchar();}
	while ( a>='0' && a<='9' ){	x=(x<<3)+(x<<1)+a-'0'; a=getchar();}return x*y;
}
#define N 30009
int n,m,fa[N]; 
int findfa(int x){
	return x == fa[ x ] ?  x : fa[x]=findfa(fa[x]);
}
void join(int a,int b){
	fa[ findfa(a) ] = findfa(b);
}
void init(){
	rep(i,0,n)	fa[i] = i; 
}
int sumfa(int x){
	int sum = 0; 
	int xfa = findfa(x);
	for (int i = 0 ; i <= n; i++)
		if ( fa[ i ] == xfa )
			sum++;
	return sum; 		
}
int main()
{
//	freopen("1.txt","r",stdin);
	srand((int)time(0));
//	std::ios::sync_with_stdio(false);
	while ( scanf("%d%d",&n,&m) != EOF ){
		if ( n == 0 && m == 0 )		break; 
		init();
		rep(i,1,m){
			int num = read(); 
			int one = read();
			rep(i,2,num){
				int two = read();
				join(one,two);
			}
		}
		rep(i,0,n)	findfa(i);	
		printf("%d\n",sumfa(0));
	}
	return 0;
}

AC code solution 2

#include<iostream>
#include<queue>
#include<cstring>
#include<string>
#include<sstream>
#include<map>
#include<vector>
#include<cstdio>
#include<iostream>
#include<cmath>
#include<algorithm>
#include<cstdlib>
#include<stack>
#include<ctime>
using namespace std; 
#define rep(i,aa,bb) for(register int i=aa;i<=bb;i++)
#define rrep(i,aa,bb) for(register int i=aa;i>=bb;i--)
#define mset(var,val)	 memset(var,val,sizeof(var))
#define LL long long 
#define eps 0.000001
#define inf 0x7f7f7f7f
#define llinf 1e18
#define exp 0.000001
#define pai 3.141592654
#define random(x)   rand()%(x)
#define lowbit(x)   x&(-x)
inline int read()
{
	int x=0,y=1;char a=getchar();while ( a>'9' || a<'0'){if ( a=='-')y=-1;a=getchar();}
	while ( a>='0' && a<='9' ){	x=(x<<3)+(x<<1)+a-'0'; a=getchar();}return x*y;
}
#define N 30009
int n,m,fa[N],sum[N]; 
int findfa(int x){
	return x == fa[ x ] ?  x : fa[x] = findfa(fa[x]);
}
void join(int a,int b){
	int afa = findfa(a);
	int bfa = findfa(b);
	if ( afa != bfa ){
		fa[ afa ] = bfa; 
		sum[ bfa ] += sum[ afa ];
	}
}
void init(){
	rep(i,0,n)	fa[i] = i,sum[i] = 1 ; 
}
int main()
{
//	freopen("1.txt","r",stdin);
	srand((int)time(0));
//	std::ios::sync_with_stdio(false);
	while ( scanf("%d%d",&n,&m) != EOF ){
		if ( n == 0 && m == 0 )		break; 
		init();
		rep(i,1,m){
			int num = read(); 
			int one = read();
			rep(i,2,num){
				int two = read();
				join(one,two);
			}
		}
		rep(i,0,n)	findfa(i);	
		printf("%d\n",sum[ findfa(0) ]);
	}
	return 0;
}

注意

void join(int a,int b){
	int afa = findfa(a);
	int bfa = findfa(b);
	if ( afa != bfa ){
		fa[ afa ] = bfa; 
		sum[ bfa ] += sum[ afa ];
	}
}

這裏 bfa 是祖先的編號，由於 fa[ afa ] = bfa;
所以這棵樹的代表結點是 bfa