C实现 LeetCode->Rotate List（双指针大法）(单链表 部分旋转)

Given a list, rotate the list to the right by k places, where k is non-negative.
 For example:
 Given 1->2->3->4->5->NULL and k = 2,
 return 4->5->1->2->3->NULL.
 
 
 双指针，没什么难点。

//
//  RotateList.c
//  Algorithms
//
//  Created by TTc on 15/6/22.
//  Copyright (c) 2015年 TTc. All rights reserved.
//
/**
*  Given a list, rotate the list to the right by k places, where k is non-negative.
For example:
Given 1->2->3->4->5->NULL and k = 2,
return 4->5->1->2->3->NULL.

双指针，没什么难点。
*/
#include "RotateList.h"
#include <stdlib.h>
#include <string.h>
#include "List.h"

/********************************************************************/
// LeetCode 答案
/********************************************************************/
struct ListNode {
int val;
struct ListNode *next;
};

struct ListNode*
rotateRight(struct ListNode* head, int k) {

if(head == NULL || head->next == NULL) return head;

struct ListNode *Tracker = head;
struct ListNode *Looper = head;

int size = 0;
while(Looper != NULL){
Looper = Looper->next;
size++;
}
k = k % size;
Looper = head;

/*主循环*/
int count = 0;
while(Looper->next != NULL){
if(count >= k) Tracker = Tracker->next;
count++;
Looper = Looper->next;
}

/*重构单链表*/
Looper->next = head;
head = Tracker->next;
Tracker->next = NULL;

return head;
}

/********************************************************************/
/********************************************************************/

/********************************************************************/
// List.c 是范性类 单链表
/********************************************************************/

ListElmt*
tt_rotateRight(ListElmt* head, int k) {

if(head == NULL || head->next == NULL) return head;

ListElmt *Tracker = head;
ListElmt *Looper = head;

int size = 0;
while(Looper != NULL){
Looper = Looper->next;
size++;
}
k = k % size;
Looper = head;

/*主循环*/
int count = 0;
while(Looper->next != NULL){
if(count >= k) Tracker = Tracker->next;
count++;
Looper = Looper->next;
}

/*重构单链表*/
Looper->next = head;
head = Tracker->next;
Tracker->next = NULL;

return head;
}

void
test_tt_rotateRight(){
List l1;
list_init(&l1, free);
int *data ;
int array[15] = {100,200,300,4000,5000,600,700,800,900,100000};
for (int i = 0; i< 10; i++) {
if ((data = (int *)malloc(sizeof(int))) == NULL)
return ;
*data = array[i];
if (list_ins_next(&l1, NULL, data) != 0)  //逐个插入元素
return;
}
print_list(&l1);

ListElmt *result = tt_rotateRight(list_head(&l1),3);
printf("result->val===%d\n",*(int *)result->data);
print_listNode(result);
}

/********************************************************************/
/********************************************************************/