Submission #1575447

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Source Code Expand

#include<bits/stdc++.h>
#include<vector>
#define N 400005
using namespace std;
vector<int> G[N];
int n,m=1,a[N],b[N],head[N],nxt[N],num[N],op[N],vis[N],dex[N],X[N],rt;
void link(int x,int y,int z)
{
	num[++m]=y,dex[m]=z,nxt[m]=head[x],head[x]=m;
	num[++m]=x,dex[m]=z,nxt[m]=head[y],head[y]=m;
}
void dfs(int t)
{
	int i;
	while(head[t]){
		i=head[t];
		head[t]=nxt[i];
		if(vis[i]) continue;
		vis[i]=vis[i^1]=1;
		dfs(num[i]);
		if(~dex[i]&1)
			X[dex[i]/2]=(i&1 ? 1 : -1);
	  }
}
void DFS(int t)
{
	int i;
	for(i=0;i<G[t].size();i++)
		X[t]-=X[G[t][i]],DFS(G[t][i]);
}
int main()
{
	int i;
	scanf("%d",&n);
	for(i=1;i<=n;i++) scanf("%d",&a[i]);
	for(i=1;i<=n;i++) scanf("%d",&b[i]);
	for(i=1;i<=n;i++){
		if(a[i]!=-1) G[a[i]].push_back(i); else rt=i;
		link(i,(a[i]==-1 ? n+1 : a[i]),2*i);
		link((b[i]==-1 ? n+1 : b[i]),i,2*i+1);
		if(a[i]>0) op[a[i]]^=1;
		if(b[i]>0) op[b[i]]^=1;
	  }
	for(i=1;i<=n;i++)
		if(op[i]){
			printf("IMPOSSIBLE");
			return 0;
		  }
 	dfs(n+1);
	DFS(rt);
	printf("POSSIBLE\n");
	for(i=1;i<=n;i++)
		printf("%d ",X[i]);
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:34:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
                ^
./Main.cpp:35:37: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  for(i=1;i<=n;i++) scanf("%d",&a[i]);
                                     ^
./Main.cpp:36:37: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  for(i=1;i<=n;i++) scanf("%d",&b[i]);
                                     ^

Judge Result