PAT 1097. Deduplication on a Linked List

#include<cstdio>
#include<set>
using namespace std;
#define M 100010
struct node{
	int data,next;
}n[M];
int list1[M],list2[M];
int first,num;
set<int> s;
void printnode(int *list,int cnt){
	for (int i = 0; i < cnt; i++){
		printf("%.5d %d ",list[i],n[list[i]].data);
		if(i!=cnt-1) 
			printf("%.5d\n",list[i+1]);
		else 
			printf("-1\n");
	}
}
int main(){
	scanf("%d%d",&first,&num);
	for (int i = 0; i < num; i++){//输入
		int t;
		scanf("%d",&t);
		scanf("%d%d",&n[t].data,&n[t].next);
	}
	int p=first;
	int cnt1=0,cnt2=0;
	while (p!=-1){//处理,建立红黑树，每次都查找
		int val=n[p].data;
		val=val>0?val:-val;
		if(s.count(val))
			list2[cnt2++]=p;
		else{
			s.insert(val);
			list1[cnt1++]=p;
		}
		p=n[p].next;
	}
	printnode(list1,cnt1);
	printnode(list2,cnt2);
	return 0;
}