谷歌笔试题 --- 环状链表去重

标签：谷歌校招笔试题

比如：1（头）->2->2->3->3->1->1（头） 去除以后的结果是1->2->3，注意头尾的1也要去掉一个。

//时间复杂度为O(N)
//空间复杂度为O(1)

//代码如下：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <climits>
#include <cmath>
#include <queue>
#include <cassert>
#include <algorithm>
#define MAXN 10010
#define RST(N)memset(N, 0, sizeof(N))
using namespace std;

typedef int data_t;

typedef struct ListNode
{
    data_t data;
    struct ListNode *next;
}LNode, *pNode;

pNode Create(int n, int *hashTable)
{
    pNode head = NULL;
    pNode p1 = NULL, p2 = NULL;
    p1 = p2 = (pNode)malloc(sizeof(LNode));
    while(n--)
    {
        cin >> p1->data;
        hashTable[p1->data]++;   //统计
        if(head == NULL)
            head = p1;
        else
            p2->next = p1;
        p2 = p1;
        p1 = (pNode)malloc(sizeof(LNode));
    }
    p2->next = head;    //指向头
    return head;
}

void uniqueListNode(pNode head, int *hashTable)
{
    assert(head != NULL);
    pNode pre = head;
    pNode cur = head->next;
    while(cur != head && cur != NULL)   //去重
    {
        pNode p = cur;
        pNode Next = cur->next;
        if(hashTable[cur->data] == 1)
            pre = cur;
        else if(hashTable[cur->data] > 1)
        {
            hashTable[cur->data]--;
            pre->next = Next;
            free(p);    //释放
        }
        cur = Next;
    }
}

int main()
{
    int n;
    while(cin >> n)
    {
        int hashTable[MAXN] = {0};   //hash存储出现的次数
        pNode head = Create(n, hashTable);    //构造一个环状单链表
        uniqueListNode(head, hashTable);   //去重
        /***** result *****/
        cout << head->data << "->";
        for(pNode p=head->next; p!=head; p=p->next)
        {
            cout << p->data;
            if(p->next != head) cout << "->";
            else cout << endl;
        }
    }
    return 0;
}

谷歌笔试题 --- 环状链表去重

标签：谷歌校招笔试题

原文地址：http://blog.csdn.net/keshacookie/article/details/47303573