从尾到头打印链表

Posted 2020-08-03 三颗心

题目：输入一个链表的头结点，从尾到头反过来打印出每个结点的值。

思路1:使用栈

思路2:递归

  1 #include<iostream>
  2 #include <stdlib.h>
  3 #include <stack>
  4 
  5 using namespace std;
  6 
  7 struct ListNode
  8 {
  9     int m_nValue;
 10     ListNode* m_pNext;
 11 };
 12 
 13 ListNode* CreateListNode(int value)
 14 {
 15     ListNode *pNode = new ListNode();
 16     pNode->m_nValue = value;
 17     pNode->m_pNext = NULL;
 18     return pNode;
 19 }
 20 
 21 void PrintListNode(ListNode* pNode)
 22 {
 23     printf("%d\\n", pNode->m_nValue);
 24 }
 25 
 26 //打印链表 
 27 void PrintList(ListNode* pHead)
 28 {
 29     ListNode* pNode = pHead;
 30     while(pNode != NULL)
 31     {
 32         cout << pNode->m_nValue<<" ";
 33         pNode=pNode->m_pNext;
 34     }
 35     cout << endl;
 36 }
 37 
 38 //在链表结尾添加一个结点 
 39 void AddToTail(ListNode** pHead, int value)
 40 {
 41     ListNode* pNew = new ListNode();
 42     pNew->m_nValue = value;
 43     pNew->m_pNext = NULL;
 44 
 45     if(*pHead == NULL)
 46     {
 47         *pHead = pNew;
 48     }
 49     else
 50     {
 51         ListNode* pNode = *pHead;
 52         while(pNode->m_pNext != NULL)
 53             pNode = pNode->m_pNext;
 54 
 55         pNode->m_pNext=pNew;
 56     }
 57 
 58 }
 59 
 60 
 61 //方法1: 用栈实现 
 62 void PrintListReversingly_Iteratively(ListNode* pHead)
 63 {
 64     ListNode* pNode = pHead;
 65     stack<ListNode*> nodes;
 66 
 67     while(pNode != NULL)
 68     {
 69         nodes.push(pNode);
 70         pNode = pNode->m_pNext;
 71     }
 72 
 73     while(!nodes.empty())
 74     {
 75         pNode = nodes.top();
 76         cout<<pNode->m_nValue<<" ";
 77         nodes.pop();
 78     }
 79     cout << endl;
 80 }
 81 
 82 //方法2: 递归 
 83 void PrintListReversingly_Recursively(ListNode* pHead)
 84 {
 85     ListNode* pNode = pHead;
 86     if(pNode != NULL)
 87     {
 88         if(pNode->m_pNext != NULL)
 89             PrintListReversingly_Recursively(pNode->m_pNext);
 90     }
 91     cout<<pNode->m_nValue<<" ";
 92 }
 93 
 94 // 1->2->3->4->5->6->7
 95 int main()
 96 {
 97     ListNode* pNode1 = CreateListNode(1);
 98     PrintList(pNode1);
 99 
100     AddToTail(&pNode1,2);
101     AddToTail(&pNode1,3);
102     AddToTail(&pNode1,4);
103     AddToTail(&pNode1,5);
104     AddToTail(&pNode1,6);
105     AddToTail(&pNode1,7);
106 
107     PrintList(pNode1);
108     
109     PrintListReversingly_Iteratively(pNode1);
110     PrintListReversingly_Recursively(pNode1);
111     
112     return 0;
113 }