Submission #4642779

---

Source Code Expand

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int N=110000;
int a[N],b[N],root1,root2,p[N*2],h[N*2],num,n,ans[N*2],f[N*2];
bool flag[N];
struct node{
	int x,y,next,k;
	bool flag;
}data[N*10];
void link(int x,int y){
	++num;
	data[num].x=x;
	data[num].y=y;
	data[num].next=h[x];
	data[num].k=num+1;
	data[num].flag=true;
	h[x]=num;
	++num;
	data[num].x=y;
	data[num].y=x;
	data[num].next=h[y];
	data[num].k=num-1;
	data[num].flag=true;
	h[y]=num;
	p[x]++;
	p[y]++;
}
void dfs1(int x){
	for(int i=h[x];i!=-1;i=data[i].next){
		if(!data[i].flag)continue;
		int v=data[i].y;
		if(x<=n&&v<=n){f[x]++;f[v]--;}
		if(x==root1&&v==root2){f[x]++;f[v]--;}
//		if(x==root2&&v==root1){f[x]++;f[v]--;}
		data[i].flag=false;
		data[data[i].k].flag=false;
		dfs1(v);
	}
}
int dfs2(int x){
	flag[x]=false;
	int num1=0;
	for(int i=h[x];i!=-1;i=data[i].next){
		int v=data[i].y;
		if(!flag[v])continue;
		num1+=dfs2(v);
	}
	ans[x]=f[x]+num1;
	return ans[x];
}
int main(){
//	freopen("4.in","r",stdin);
	scanf("%d",&n);
	memset(h,-1,sizeof h);
	for(int i=1;i<=n;i++){
		scanf("%d",&a[i]);
		if(a[i]!=-1)link(a[i],i);
		else root1=i;
	}
	for(int i=1;i<=n;i++){
		scanf("%d",&b[i]);
		if(b[i]!=-1)link(b[i]+n,i+n);
		else root2=i+n;
	}
	link(root1,root2);
	for(int i=1;i<=n;i++){
		if((p[i]%2)!=(p[i+n]%2)){
			printf("IMPOSSIBLE\n");
			return 0;
		}else if(p[i]%2==1)link(i,i+n);
	}
	printf("POSSIBLE\n");
	dfs1(root1);
	for(int i=1;i<=n;i++)printf("%d ",f[i]);
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:55:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
                ^
./Main.cpp:58:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&a[i]);
                    ^
./Main.cpp:63:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&b[i]);
                    ^

Judge Result