Submission #1694174

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Source Code Expand

//2017-10-19
//miaomiao
//
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <iostream>
#include <algorithm>
#include <vector>
 
using namespace std;
 
#define pb push_back
#define For(i, a, b) for(int i = (a); i <= (int)(b); ++i)
 
#define N (100000+5)
 
vector<int> G[N];
int ans, c01[N], c10[N];
 
#define v G[now][i]
 
void Dfs(int now, int F){
	int s01 = 0, s10 = 0;
	For(i, 0, G[now].size()-1) if(v != F){
		Dfs(v, now);
		s01 += c01[v]; s10 += c10[v];
	}
	if(s01 == s10-1){ans += s01 + s10 - 1; return;}

	int a;
	if(s01 > s10){
		a = s01;
		ans += a + (a-1);
		c10[now] += (a-1) - s10;
	}else{
		a = s10+1;
		ans += a + (a-1);
		c01[now] += a - s01;
	}
}

#undef v
 
int main(){
	int n, m, u, v;
	
	scanf("%d%d", &n, &m);
	For(i, 1, m){
		scanf("%d%d", &u, &v);
		G[u].pb(v); G[v].pb(u);
	}
	if(m != n-1) return 0;

	if(n == 1){
		puts("-1"); return 0;
	}
 
	Dfs(1, 0);
 
	if(c01[1] || c10[1]) puts("-1");
	else printf("%d\n", ans>>1);
 
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:49:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &n, &m);
                       ^
./Main.cpp:51:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &u, &v);
                        ^

Judge Result