【经典算法】: 求链表中倒数第K个结点

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链表中倒数第K个节点的求法
方法有两个：
1，先算出来链表中有多少个节点，假设为count个，然后顺序遍历
找到count-k个时就可以截至

2，先对整个链表反序，然后倒过来找第K个即可

下面给出第一种方法：

static void GetKNumber(struct node** head_ref,int k){    int count = 0,temp=0;    struct node* head = *head_ref;    struct node* head_trail = *head_ref;    while(head!=NULL){        count++;        head = head->next;    }    while(head_trail!=NULL){        temp++;        if(temp-1==count-k){            cout<<"the k data is"<<head_trail->data<<endl;        }        head_trail = head_trail->next;    }}

上面是函数，然后下面是完整的程序：

#include <iostream>#include <stdio.h>#include <stdlib.h>using namespace std;struct node{    int data;    struct node* next;};void push(struct node** head_ref,int new_data){    struct node* new_node = (struct node*) malloc(sizeof(struct node));    new_node->data = new_data;    new_node->next = (*head_ref);    (*head_ref) = new_node;}static void reverse(struct node** head_ref){      //用于翻转，把所有的对应关系都反过来    struct node* prev = NULL;    struct node* current = *head_ref;    struct node* next;    while(current!=NULL){        next = current->next;        current->next = prev;     //倒过来指        prev = current;        current = next;  //用来将循环往后拖    }    *head_ref = prev;   //代表着最后一个}//链表中倒数第K个节点static void GetKNumber(struct node** head_ref,int k){    int count = 0,temp=0;    struct node* head = *head_ref;    struct node* head_trail = *head_ref;    while(head!=NULL){        count++;        head = head->next;    }    while(head_trail!=NULL){        temp++;        if(temp-1==count-k){            cout<<"the k data is"<<head_trail->data<<endl;        }        head_trail = head_trail->next;    }}void printList(struct node *head)    {        struct node *temp = head;        while(temp != NULL)        {            printf("%d  ", temp->data);            temp = temp->next;        }    }int main(){    struct node* head = NULL;    push(&head,20);    push(&head,4);    push(&head,15);    push(&head,85);    push(&head,60);    push(&head,100);    printList(head);    GetKNumber(&head,2);    reverse(&head);    cout<<endl<<"翻转后的结果"<<endl;    printList(head);    return 0;}

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