Submission #1444486

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Source Code Expand

#include <stdio.h>
#include <algorithm>
#include <vector>
using namespace std;

vector<int> G[100010];
int N,A,B;

int dfs(int x, int l)
{
	vector<int> u;
	for (int y : G[x]) if (y != l){
		u.push_back(dfs(y,x));
	}

	int mx = 0;
	for (int i=0;i<u.size();i++) mx = max(mx,u[i]);
	if (G[x].size() == 2){
		mx++;
		if (u.size() == 2){
			B = max(B, u[0] + u[1] + 1);
		}
		else{
			B = max(B,mx);
		}
	}
	else{
		sort(u.rbegin(),u.rend());
		if (u.size() >= 2){
			B = max(B, u[0] + u[1]);
		}
	}
	return mx;
}

int main()
{
	scanf ("%d",&N);
	for (int i=1;i<N;i++){
		int x,y; scanf ("%d %d",&x,&y);
		G[x].push_back(y);
		G[y].push_back(x);
	}
	for (int i=1;i<=N;i++) if (G[i].size() == 1) A++;

	dfs(1,0);
	printf ("%d\n",A+B);

	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:38:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf ("%d",&N);
                 ^
./Main.cpp:40:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   int x,y; scanf ("%d %d",&x,&y);
                                 ^

Judge Result