Islands (disjoint-set)

P1714] [Week4 islands

Time limit: 10000 MS   Space limitations: 128000 KB

Problem Description

N-islands on the lake, numbered from 1 ~ n. Now to make the bridge connecting the island on the lake. Bridge two-way traffic.

Input Format

Input of the first line has two integers n, m.
Followed by m rows, each row in order of time is a query.
Each line q represents an integer of inquiry content:
if q = 1, then the next number is two islands a, b (a ≠ b) ;
if q = 2, then the next number is an island c.

Output Format

For each query, the answer in sequence as the respective output line:
Q =. 1 applies: If a, b to each other up, output Yes; if a, b is not reachable to each other, the output No, and built in between a, b a bridge.
when q = 2: Output an integer x, it can reach starting from the islands c x (excluding itself c).

Sample input

5 9
1 2 3
1 3 2
2 1
2 2
1 4 5
1 2 4
1 2 5
2 4
2 5

Sample Output

No
Yes
0
1
No
No
Yes
3
3

prompt

To 100% of the data, 2≤n≤10,000, 1≤m≤30,000.

 

problem analysis:

Question 1: Query a, b two elements are in the same collection, if not, it will merge two sets.

Question 2: Ask where the number of elements of the set of elements c.

 

When adding the combined number of the sets

code:

//
#include<bits/stdc++.h>
using namespace std;
#define maxnn 30100
int f[maxnn],cnt[maxnn];
int q;
int n,m;
int gf(int v)
{
    return f[v]==v? v: f[v]=gf(f[v]);
}
void merge(int x,int y)
{
    int fx=gf(x);
    int fy=gf(y);
    if(fx!=fy)
    {
        f[fx]=fy;
        cnt[fy]+=cnt[fx];
    } 
}
int main()
{
    cin>>n>>m;
    int x,y;
    
    for(int i=1;i<=n;i++)
    f[i]=i,cnt[i]=1;
    for(int i=1;i<=m;i++)
    {
        cin>>q;
        if(q==1)
        {
            cin>>x>>y;
            if(gf(x)==gf(y))
            cout<<"Yes"<<endl;
            else
            cout<<"No"<<endl;
            if(!(gf(x)==gf(y)))
            merge(x,y);
        }
        else
        {
            cin>>x;
            cout<<cnt[gf(x)]-1<<endl;
        }
    }
    
    
    
}