1052 Linked List Sorting (25分)

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本文介绍了一种基于静态链表的链表排序算法，通过初始化节点并利用比较函数进行整体比较，实现链表中节点按数值大小升序排列。特别关注了处理孤立节点的方法，确保所有节点正确排序。

A linked list consists of a series of structures, which are not necessarily adjacent in memory. We assume that each structure contains an integer key and a Next pointer to the next structure. Now given a linked list, you are supposed to sort the structures according to their key values in increasing order.
Input Specification:

Each input file contains one test case. For each case, the first line contains a positive N (<105) and an address of the head node, where N is the total number of nodes in memory and the address of a node is a 5-digit positive integer. NULL is represented by −1.

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

Address Key Next

where Address is the address of the node in memory, Key is an integer in [−105,105], and Next is the address of the next node. It is guaranteed that all the keys are distinct and there is no cycle in the linked list starting from the head node.
Output Specification:

For each test case, the output format is the same as that of the input, where N is the total number of nodes in the list and all the nodes must be sorted order.
Sample Input:

5 00001
11111 100 -1
00001 0 22222
33333 100000 11111
12345 -1 33333
22222 1000 12345

Sample Output:

5 12345
12345 -1 00001
00001 0 11111
11111 100 22222
22222 1000 33333
33333 100000 -1

题意：输入一个链表，按数值大小升序排序
思路：由于地址比较小，我们使用静态链表来表达，flag用来表示是否存在节点；利用cmp进行整体比较，当有一个节点不存在时放入后面，否则按数值进行比较；
注意：有可能存在孤立点，所以需要从头遍历

#include<stdio.h>
#include<algorithm>
using namespace std;
const int maxn=100010;
struct node{
	int address,next,data;
	bool flag;
}nodes[maxn];
bool cmp(node a,node b){
	if(a.flag==false||b.flag==false){//有一个非链表节点时
		return a.flag>b.flag;
	}else{
		return a.data<b.data;
	}
}
int main(){
	for(int i=0;i<maxn;i++){//初始化
		nodes[i].flag=false;
	}
	int n,start;
	scanf("%d%d",&n,&start);
	int address,next,data;
	for(int i=0;i<n;i++){
		scanf("%d%d%d",&address,&data,&next);
		nodes[address].address=address;
		nodes[address].data=data;
		nodes[address].next=next;
	}
	int p=start,count=0;
	while(p!=-1){//确定链表节点，排除孤立点
		nodes[p].flag=true;
		count++;
		p=nodes[p].next;
	}
	if(count==0){//特殊情况判断
		printf("0 -1");
	}else{
		sort(nodes,nodes+maxn,cmp);
	    printf("%d %05d\n",count,nodes[0].address);
	    for(int i=0;i<count;i++){
		if(i!=count-1){
			printf("%05d %d %05d\n",nodes[i].address,nodes[i].data,nodes[i+1].address);
		}else{
			printf("%05d %d -1\n",nodes[i].address,nodes[i].data);			
		    }		
	    }	
	}
}