Submission #1693946

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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];
bool col[N];
int ans;

#define v G[now][i]

void Dfs(int now, int F){
	For(i, 0, G[now].size()-1)
		if(v != F) Dfs(v, now);
	if(!col[now]) col[now] ^= 1, col[F] ^= 1, ++ans;
}

#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(n == 1){
		puts("-1"); return 0;
	}

	Dfs(1, 0);

	if(col[0]) puts("-1");
	else printf("%d\n", ans);

	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:36:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &n, &m);
                       ^
./Main.cpp:38:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &u, &v);
                        ^

Judge Result