Language: C++

#include <bits/stdc++.h>
#define ll long long
#define INF 999999999
#define MOD 1000000007

using namespace std;

typedef pair<int,int>P;

const int MAX_N = 100000;

int par[MAX_N];
int rank[MAX_N];

void initial(int n){		//?????????
	for(int i=0;i<n;i++){
		par[i] = i;
		rank[i] = 0;
	}
}

int find(int x){		//??¨??????????±???????
	if(par[x] == x){
		return x;
	}else{
		return par[x] = find(par[x]);
	}
}

void unite(int x,int y){
	x = find(x);
	y = find(y);
	if(x == y) return;
	if(rank[x] < rank[y]){
		par[x] = y;
	}else{
		par[y] = x;
		if(rank[x] == rank[y])
			rank[x]++;
	}
}

bool same(int x,int y){
	return find(x) == find(y);
}

int main()
{
	int n,m,q;
	int a,b;
	cin >> n;
	cin >> m;
	initial(n);
	for(int i=0;i<m;i++){
		cin >> a;
		cin >> b;
		unite(a,b);
	}
	cin >> q;
	for(int i=0;i<q;i++){
		cin >> a;
		cin >> b;
		if(same(a.b)){
			cout << "yes\n";
		}else{
			cout << "no\n";
		}
	}
}

Compiler output:
a.cc: In function 'void initial(int)':
a.cc:18:17: error: reference to 'rank' is ambiguous
   18 |                 rank[i] = 0;
      |                 ^~~~
In file included from /usr/include/c++/14/bits/stl_pair.h:60,
                 from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/type_traits:1437:12: note: candidates are: 'template<class> struct std::rank'
 1437 |     struct rank
      |            ^~~~
a.cc:13:5: note:                 'int rank [100000]'
   13 | int rank[MAX_N];
      |     ^~~~
a.cc: In function 'void unite(int, int)':
a.cc:34:12: error: reference to 'rank' is ambiguous
   34 |         if(rank[x] < rank[y]){
      |            ^~~~
/usr/include/c++/14/type_traits:1437:12: note: candidates are: 'template<class> struct std::rank'
 1437 |     struct rank
      |            ^~~~
a.cc:13:5: note:                 'int rank [100000]'
   13 | int rank[MAX_N];
      |     ^~~~
a.cc:34:22: error: reference to 'rank' is ambiguous
   34 |         if(rank[x] < rank[y]){
      |                      ^~~~
/usr/include/c++/14/type_traits:1437:12: note: candidates are: 'template<class> struct std::rank'
 1437 |     struct rank
      |            ^~~~
a.cc:13:5: note:                 'int rank [100000]'
   13 | int rank[MAX_N];
      |     ^~~~
a.cc:38:20: error: reference to 'rank' is ambiguous
   38 |                 if(rank[x] == rank[y])
      |                    ^~~~
/usr/include/c++/14/type_traits:1437:12: note: candidates are: 'template<class> struct std::rank'
 1437 |     struct rank
      |            ^~~~
a.cc:13:5: note:                 'int rank [100000]'
   13 | int rank[MAX_N];
      |     ^~~~
a.cc:38:31: error: reference to 'rank' is ambiguous
   38 |                 if(rank[x] == rank[y])
      |                               ^~~~
/usr/include/c++/14/type_traits:1437:12: note: candidates are: 'template<class> struct std::rank'
 1437 |     struct rank
      |            ^~~~
a.cc:13:5: note:                 'int rank [100000]'
   13 | int rank[MAX_N];
      |     ^~~~
a.cc:39:25: error: reference to 'rank' is ambiguous
   39 |                         rank[x]++;
      |                         ^~~~
/usr/include/c++/14/type_traits:1437:12: note: candidates are: 'template<class> struct std::rank'
 1437 |     struct rank
      |            ^~~~
a.cc:13:5: note:                 'int rank [100000]'
   13 | int rank[MAX_N];
      |     ^~~~
a.cc: In function 'int main()':
a.cc:63:27: error: request for member 'b' in 'a', which is of non-class type 'int'
   63 |                 if(same(a.b)){
      |                           ^