Submission #2198318

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Source Code Expand

#include<iostream>
#include<cstdio>
#include<vector>
#include<cstdlib>
using namespace std;
int n;
vector<int>G[100010];
int state[100010];
int ans;
void dfs(int x,int p)
{
	int all[22];
	for(int i=0;i<=20;i++)all[i]=0;
	state[x]=0;
	for(int i=0;i<G[x].size();i++)
	{
		int y=G[x][i];
		if(y==p)continue;
		dfs(y,x);
		state[x]|=state[y];
	    for(int j=0;j<=20;j++)
	    {
	    	if(state[y]>>j&1)
	    	{
	    		all[j]++;
	    	}
	    }
	}
	int res=0;
	for(int i=20;i>=0;i--)
	{
		if(all[i]>1)
		{
			res=i+1;
			break;
		}
	}
	for(int i=res;i<=20;i++)
	{
		if(state[x]>>i&1)continue;
		res=i;
		break;
	}
	state[x]|=(1<<res);
	for(int i=0;i<res;i++)if(state[x]>>i&1)state[x]^=(1<<i);
	ans=max(ans,res);
}
int main()
{
	scanf("%d",&n);
	for(int i=1;i<n;i++)
	{
		int a,b;
		scanf("%d%d",&a,&b);
		G[a].push_back(b);
		G[b].push_back(a); 
	}
	dfs(1,0);
	printf("%d",ans);
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:50:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
                ^
./Main.cpp:54:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&a,&b);
                      ^

Judge Result