剑指offer 面试题15 链表中的倒数第k个节点

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两个指针，相距为k（不是k-1！！）

注意：k的取值可能会很诡异，注意判断，见测试用例

#include <stdio.h>typedef struct SLinkNode{int value;struct SLinkNode *next;}LinkNode;void addToLink(LinkNode **head, int i);void printfLink(LinkNode *head);LinkNode* lastK(LinkNode *head, int k);int main(int argc, char *argv[]){//测试用例：设链表长n,k=n,k=o, 0<k<n, k>n ,链表头传入NULL int i;LinkNode *head = NULL;for(i=0 ; i<10 ; i++){addToLink(&head, i);}printfLink(head);LinkNode *result = lastK(NULL, 11);if(result != NULL){int v = result->value;printf("%d\n", v );}return 0;}LinkNode* lastK(LinkNode *head, int k){if(k <= 0)return NULL;LinkNode *first, *second;first = head;second = head;int i = 0;while(first != NULL){first = first->next;i++;if(i == k)//!!!break;}if(first == NULL)return NULL;while((first != NULL) && (second != NULL)){first = first->next;second = second->next;}return second;}void addToLink(LinkNode **head, int i){LinkNode *t = (LinkNode*)malloc(sizeof(LinkNode));t->value = i;t->next = NULL;if(t == NULL)return;if(*head == NULL)*head = t;else{LinkNode *t2 = *head;while(t2->next != NULL)t2 = t2->next;t2->next = t;}}void printfLink(LinkNode *head){while(head != NULL){printf("%d\t", head->value);head = head->next;}printf("\n");}

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