個人學習記錄，代碼難免不盡人意
Given a singly linked list L with integer keys, you are supposed to remove the nodes with duplicated absolute values of the keys. That is, for each value K, only the first node of which the value or absolute value of its key equals K will be kept. At the mean time, all the removed nodes must be kept in a separate list. For example, given L being 21→-15→-15→-7→15, you must output 21→-15→-7, and the removed list -15→15.

Input Specification:
Each input file contains one test case. For each case, the first line contains the address of the first node, and a positive N (≤10 5 ) which is the total number of nodes. The address of a node is a 5-digit nonnegative integer, and NULL is represented by ?1.

Then N lines follow, each describes a node in the format:

Address Key Next
where Address is the position of the node, Key is an integer of which absolute value is no more than 10 4, and Next is the position of the next node.

Output Specification:
For each case, output the resulting linked list first, then the removed list. Each node occupies a line, and is printed in the same format as in the input.

Sample Input:
00100 5
99999 -7 87654
23854 -15 00000
87654 15 -1
00000 -15 99999
00100 21 23854
Sample Output:
00100 21 23854
23854 -15 99999
99999 -7 -1
00000 -15 87654
87654 15 -1

#include<cstdio>
#include<iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<cmath>
#include<map>
#include<set>
using namespace std;
struct node{int data;int address;int next; 
}Node[100010];int main(){int first,n,k;scanf("%d %d",&first,&n);for(int i=0;i<n;i++){int address,data,next;scanf("%d%d%d",&address,&data,&next);node a;a.address=address;a.data=data;a.next=next;Node[address]=a;}set<int> s;s.insert(abs(Node[first].data));int now=Node[first].address;int newfirst=-1;int newtemp=-1;bool flag=true;while(Node[now].next!=-1){node no=Node[now];if(s.find(abs(Node[no.next].data))==s.end()){s.insert(abs(Node[no.next].data));now=no.next;}else{Node[now].next=Node[no.next].next;if(flag){newfirst=no.next;newtemp=newfirst;flag=false;}else{Node[newtemp].next=no.next;newtemp=no.next;}}}now=Node[first].address;while(now!=-1){if(Node[now].next==-1)printf("%05d %d -1\n",Node[now].address,Node[now].data);else printf("%05d %d %05d\n",Node[now].address,Node[now].data,Node[now].next);now=Node[now].next;}if(newfirst!=-1){Node[newtemp].next=-1;int newnow=Node[newfirst].address;while(newnow!=-1){if(Node[newnow].next==-1)printf("%05d %d -1\n",Node[newnow].address,Node[newnow].data);else printf("%05d %d %05d\n",Node[newnow].address,Node[newnow].data,Node[newnow].next);newnow=Node[newnow].next;}}}

本題真的踩了不少坑，我的做法和《算法筆記》略有不同，其中要注意的地方有1.注意邊界，比如當前node的next值為-1，再讓node=node.next就很有可能出錯，應該事先判斷。一定要注意邊界值。并且，我的做法還要判斷是不是有要刪除的節點（即原鏈表中是否出現了兩個絕對值一樣的數），如果沒有的話有些操作不應該出現。