Submission #779458

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

int N,M,S;
list<int> edge [200001];
bool ans [200001];

class union_find{
	public:
	union_find(int n)
		:par(n + 1)
	{
		for(int i = 1;i <= n;i++){
			par [i] = i;
		}
	}
	int find(int x)
	{
		if(par [x] == x){
			return x;
		}
		return par [x] = find(par [x]);
	}
	void connect(int x,int y)
	{
		x = find(x);
		y = find(y);

		if(x != y){
			par [y] = x;
		}
	}
	bool same(int x,int y)
	{
		return find(x) == find(y);
	}
	private:
		vector<int> par;
};

int main()
{
	scanf("%d%d%d",&N,&M,&S);
	for(int i = 0;i < M;i++){
		int U,V;
		scanf("%d%d",&U,&V);
		edge [U].push_back(V);
		edge [V].push_back(U);
	}

	union_find uf(N);
	for(int i = N;i >= 1;i--){
		for(auto it = edge [i].begin();it != edge [i].end();it++){
			if(*it > i){
				uf.connect(i,*it);
			}
		}
		ans [i] = uf.same(i,S);
	}

	for(int i = 1;i <= N;i++){
		if(ans [i]){
			printf("%d\n",i);
		}
	}

	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:43:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d",&N,&M,&S);
                          ^
./Main.cpp:46:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&U,&V);
                      ^

Judge Result