Submission #1771606

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Source Code Expand

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

int n,t,w,cnt;
int fa[200010],d[200010];
pair<int,int> q[4000010];
map<int,int> h[200010];

int find(int x)
{return fa[x]==x?x:fa[x]=find(fa[x]);
}

int main()
{int i,j,x,y,k;
 map<int,int>::iterator p;
 
 scanf("%d",&n);
 for(i=1;i<n;i++)
 {	scanf("%d%d",&x,&y);
 	h[x][y]=1;
 	h[y][x]=1;
 	d[x]++;
 	d[y]++;
 }
 t=1;
 w=0;
 for(i=1;i<n;i++)
 {	scanf("%d%d",&x,&y);
 	h[x][y]++;
 	h[y][x]++;
 	d[x]++;
 	d[y]++;
 	if(h[x][y]==2) q[++w]=make_pair(x,y);
 }
 for(i=1;i<=n;i++) fa[i]=i;
 while(t<=w)
 {	x=find(q[t].first);
 	y=find(q[t].second);
 	if(x!=y)
 	{	if(d[x]<d[y]) swap(x,y);
 		h[x][y]-=2;
 		h[y][x]-=2;
 		for(p=h[y].begin();p!=h[y].end();p++)
 		{	if((*p).second==0) continue;
	 		k=(h[x][(*p).first]+=(*p).second);
 			h[(*p).first][x]+=(*p).second;
 			h[(*p).first][y]-=(*p).second;
 			if(k==2)
 				q[++w]=make_pair(x,(*p).first);
 		}
 		h[y].clear();
		d[x]+=d[y]-2;
		fa[y]=x;
		cnt++;
	}
 	t++;
 }
 printf("%s\n",cnt==n-1?"YES":"NO");
 return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:17:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
                ^
./Main.cpp:19:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  { scanf("%d%d",&x,&y);
                       ^
./Main.cpp:28:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  { scanf("%d%d",&x,&y);
                       ^

Judge Result