hdu Disjoint-set problems

Disjoint-set namely Union-Find set!

hdu 3172 virtual friends  http://acm.hdu.edu.cn/showproblem.php?pid=3172

Yes! A very interesting problem!

Whenever a friendship is formed,printf the number of the peoplein the social network.

OK, I failed lots of time. And all are "Time Limit Exceeded".

But to my surprise!  I just replace the "cin" with “scanf” ,"cout" with "printf" in the code,and accepted!

learned:  scanf/printf  is more efficient than cin/cout;

#include<iostream>
#include<cstring>
#include<string>
#include<map>
#include<cstdio>
using namespace std;
int f[200005],num[200005];
void sequence()
{
    int i;
    for(i=1;i<200005;i++)
    {
        f[i]=i;
        num[i]=1;
    }
}
int find(int x)
{
    if(x!=f[x])
        f[x]=find(f[x]);
    return f[x];

}
void Union(int x,int y)
{
     x=find(x);
     y=find(y);
     if(x==y)
     {
         printf("%d\n",num[x]);
     }
     else
     {
         f[y]=x;
         num[x]+=num[y];
        printf("%d\n",num[x]);
     }
}
int main()
{
    int t;
    map<string,int>match;
    while(scanf("%d",&t)!=EOF)
    {
        int k;
        string name1,name2;
        while(t--)
        {
            sequence();
            match.clear();
            scanf("%d",&k);
            int s=1;
            while(k--)
            {
                cin>>name1>>name2;
                if(match.find(name1)==match.end())
                {
                    s++;match[name1]=s;
                }
                if(match.find(name2)==match.end())
                {
                    s++;match[name2]=s;
                }
                Union(match[name1],match[name2]);
            }
        }
    }
    return 0;
}

            
            

        

Post by heat_nan             @2013-03-17       12:03