Submission #1691806

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Source Code Expand

#include<bits/stdc++.h>
#define N 100005
using namespace std;
int n,m,sm[N],tg[N],sz[N],fa[N];
int to[N*2],fst[N],nxt[N*2],l;
void biu()
{
	puts("-1");
	exit(0);
}
void link(int x,int y)
{
	to[++l]=y;nxt[l]=fst[x];fst[x]=l;
	to[++l]=x;nxt[l]=fst[y];fst[y]=l;
}
void dfs(int x)
{
	sm[x]=tg[x]=tg[fa[x]]^1;
	sz[x]=1;
	for (int i=fst[x];i;i=nxt[i])
		if (to[i]!=fa[x])
		{
			fa[to[i]]=x;
			dfs(to[i]);
			sm[x]+=sm[to[i]];
			sz[x]+=sz[to[i]];
		}
}
int main()
{
	scanf("%d%d",&n,&m);
	for (int i=1;i<=m;i++)
	{
		int x,y;
		scanf("%d%d",&x,&y);
		link(x,y);
	}
	if (m==n-1)
	{
		dfs(1);
		if (sm[1]*2!=n) biu();
		int Ans=0;
		for (int i=2;i<=n;i++)
			Ans+=abs(sm[i]*2-sz[i]);
		printf("%d\n",Ans);
	}
	else
	{
		
	}
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:31:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&n,&m);
                     ^
./Main.cpp:35:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&x,&y);
                      ^

Judge Result