836. Merge Set + Union Search Path Compression

There are a total of n numbers, numbered 1∼n, and each number is in a set at the beginning.

Now to perform m operations, there are two types of operations:

M ab, merge the sets of the two numbers numbered a and b. If the two numbers are already in the same set, ignore this operation;
Q ab, ask whether the two numbers numbered a and b are in the same set. In a set;
input format
Enter the integers n and m on the first line.

Next m lines, each line contains an operation instruction, the instruction is one of M ab or Q ab .

Output format
For each query command Q ab, output a result, if a and b are in the same set, output Yes, otherwise output No.

One line for each result.

Data range
1≤n,m≤105
Input example:
4 5
M 1 2
M 3 4
Q 1 2
Q 1 3
Q 3 4
Output example:
Yes
No
Yes

#include<bits/stdc++.h>
using namespace std;
const int N = 100010;

int p[N];

int find(int a) //返回x的祖宗结点 + 路径压缩
{
    
    
    if(a != p[a]) p[a] = find(p[a]);
    return p[a];
}

int main()
{
    
    
    int n, m;
    cin >> n >> m;
    
    for(int i=1; i<=n; i++) p[i] = i;
    
    char op;
    int a, b;
    while(m--) {
    
    
        cin >> op;
        cin >> a >> b;
        if(op == 'M') {
    
    
            p[find(a)] = find(b);
        }
        else {
    
    
            if(find(a) == find(b)) puts("Yes");
            else puts("No");
        }
    }
    
    return 0;
}