用c写算法2[链表中倒数第k个结点]
题目:输入一个链表,输出这个链表中倒数第k个结点
解法:
#include <stdio.h> #include <stdlib.h> #include <string.h> struct ListNode { int m_nValue; struct ListNode * m_pNext; }; typedef struct ListNode ListNode; typedef ListNode * LISTNODEPTR; ListNode * FindKthToTail(ListNode *, unsigned int); void insert(LISTNODEPTR * head, int value); void printList(LISTNODEPTR head); int main(int argc, char const *argv[]) { LISTNODEPTR HeadA = NULL, tailA = NULL, HeadB = NULL; insert(&HeadA, 10); insert(&HeadA, 20); insert(&HeadA, 30); printList(HeadA); LISTNODEPTR knode; knode = FindKthToTail(HeadA, 0); if (knode != NULL) printf("%d\n", knode->m_nValue); else printf("Null\n"); return 0; } void insert(LISTNODEPTR * head, int value) { LISTNODEPTR newPtr, previousPtr, currentPtr; newPtr = malloc(sizeof(LISTNODEPTR)); if (newPtr != NULL) { newPtr->m_nValue = value; newPtr->m_pNext = NULL; if(*head == NULL) { *head = newPtr; } else { newPtr->m_pNext = *head; *head = newPtr; } } else { printf("%d not inserted. No Memory available\n", value); } } void printList(LISTNODEPTR head) { LISTNODEPTR ptr; for(ptr = head; ptr != NULL; ptr = ptr->m_pNext) { printf("%d-->", ptr->m_nValue); } printf("NULL\n"); } ListNode * FindKthToTail(ListNode * pListNode, unsigned int k) { if (pListNode == NULL || k == 0) { return NULL; } LISTNODEPTR frontptr = pListNode, backptr = pListNode; int i = 0; for (; i < k-1; i++) { if (frontptr->m_pNext) { frontptr = frontptr->m_pNext; } else { return NULL; } } while (frontptr->m_pNext != NULL) { frontptr = frontptr->m_pNext; backptr = backptr->m_pNext; } return backptr; }
posted on 2013-03-27 16:17 jiyiyouxin 阅读(145) 评论(0) 编辑 收藏 举报