poj 1703 Find them, Catch them

Find them, Catch them

Time Limit: 1000MS		Memory Limit: 10000K
Total Submissions: 20728		Accepted: 6126

Description

The police office in Tadu City decides to say ends to the chaos, as launch actions to root up the TWO gangs in the city, Gang Dragon and Gang Snake. However, the police first needs to identify which gang a criminal belongs to. The present question is, given two criminals; do they belong to a same clan? You must give your judgment based on incomplete information. (Since the gangsters are always acting secretly.)

Assume N (N <= 10^5) criminals are currently in Tadu City, numbered from 1 to N. And of course, at least one of them belongs to Gang Dragon, and the same for Gang Snake. You will be given M (M <= 10^5) messages in sequence, which are in the following two kinds:

1. D [a] [b]
where [a] and [b] are the numbers of two criminals, and they belong to different gangs.

2. A [a] [b]
where [a] and [b] are the numbers of two criminals. This requires you to decide whether a and b belong to a same gang.

Input

The first line of the input contains a single integer T (1 <= T <= 20), the number of test cases. Then T cases follow. Each test case begins with a line with two integers N and M, followed by M lines each containing one message as described above.

Output

For each message "A [a] [b]" in each case, your program should give the judgment based on the information got before. The answers might be one of "In the same gang.", "In different gangs." and "Not sure yet."

Sample Input

1
5 5
A 1 2
D 1 2
A 1 2
D 2 4
A 1 4

Sample Output

Not sure yet.
In different gangs.
In the same gang.

并查集的题，需要一些小技巧来表明是否是在同一个帮派中
注意在更新的时候需要做一些处理

#include<iostream>
#include<cmath>
using namespace std;

int father[100001];
int rank[100001];

void make_set(int n)
{
    int i;
    for(i=0;i<=n;i++)
    {
        father[i]=i;
        rank[i]=0;
    }
}

int find_set(int n)
{
    int pa = father[n];
    if(father[n]==n)
        return n;
    father[n] = find_set(father[n]);
    rank[n] = (rank[n]+rank[pa])%2;
    return father[n];
}

void union_set(int a, int b)
{
    int fa = find_set(a);
    int fb = find_set(b);
    if(fa!=fb)
    {
        father[fa] = fb;
        rank[fa] = (rank[a]+rank[b]+1)%2;
    }
}

int main()
{
    int t;
    int n, m;
    char op;
    int a, b;
    freopen("e:\\data.txt", "r", stdin);        
    freopen("e:\\out.txt", "w", stdout); 
    cin>>t;
    while(t--)
    {
        cin>>n>>m;
        make_set(n);
        while(m--)
        {
            cin>>op;
            scanf("%d%d",&a,&b);
            int p = find_set(a);
            int q = find_set(b);
            if(op=='A')
            {
                if(p==q && rank[a] == rank[b])
                    cout<<"In the same gang."<<endl;
                else if(p==q)
                    cout<<"In different gangs."<<endl;
                else
                    cout<<"Not sure yet."<<endl;
            }
            else
            {
                    union_set(a, b);
            }
        }
    }
    return 0;
}