Submission #6374977

---

Source Code Expand

#include <cstdio>
#include <vector>

using namespace std;
vector<int> eds[100008];
vector<int> dirs[100008];
vector<int> revs[100008];
int degs[100008];

void run(int cur) {
	for(int i=0;i<eds[cur].size();i++) {
		if(dirs[cur][i] == 0) {
			int to = eds[cur][i];
			int rv = revs[cur][i];
			dirs[cur][i] = 1;
			dirs[to][rv] = 2;
			run(to);
		}
	}
}

int main() {
	int N, M;
	scanf("%d%d",&N, &M);
	for(int i=0;i<M;i++) {
		int a, b;
		scanf("%d%d",&a, &b);
		degs[a]++;
		degs[b]++;
		eds[a].push_back(b);
		dirs[a].push_back(0);
		revs[a].push_back(eds[b].size());
		eds[b].push_back(a);
		dirs[b].push_back(0);
		revs[b].push_back(eds[a].size() - 1);
	}
	for(int i=1;i<=N;i++) {
		if(degs[i] % 2) {
			printf("-1\n");
			return 0;
		}
	}
	for(int i=1;i<=N;i++) run(i);
	for(int i=1;i<=N;i++) {
		for(int j=0;j<eds[i].size();j++) {
			if(dirs[i][j] == 1) printf("%d %d\n", i, eds[i][j]);
		}
	}
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:24:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&N, &M);
                      ^
./Main.cpp:27:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&a, &b);
                       ^

Judge Result