Problem
You are given an array of positive and negative integers. If a number n at an index is positive, then move forward n steps. Conversely, if it"s negative (-n), move backward n steps. Assume the first element of the array is forward next to the last element, and the last element is backward next to the first element. Determine if there is a loop in this array. A loop starts and ends at a particular index with more than 1 element along the loop. The loop must be "forward" or "backward".
Example 1: Given the array [2, -1, 1, 2, 2], there is a loop, from index 0 -> 2 -> 3 -> 0.
Example 2: Given the array [-1, 2], there is no loop.
Note: The given array is guaranteed to contain no element "0".
Can you do it in O(n) time complexity and O(1) space complexity?
Solutionclass Solution { public boolean circularArrayLoop(int[] nums) { if (nums == null || nums.length <= 2) return false; for (int i = 0; i < nums.length; i++) { if (nums[i] == 0) return false; int slow = i, fast = getIndex(nums, i); while (nums[fast] * nums[i] > 0 && nums[getIndex(nums, fast)] * nums[i] > 0) { if (slow == fast) { if (slow == getIndex(nums, slow)) break; return true; } slow = getIndex(nums, slow); fast = getIndex(nums, getIndex(nums, fast)); } slow = i; int pre = nums[i]; while (nums[slow] * pre > 0) { int next = getIndex(nums, slow); nums[slow] = 0; slow = next; } } return false; } private int getIndex(int[] nums, int i) { int len = nums.length; int next = i+nums[i]; return next >= 0 ? next%len : next%len+len; } }
文章版權(quán)歸作者所有,未經(jīng)允許請(qǐng)勿轉(zhuǎn)載,若此文章存在違規(guī)行為,您可以聯(lián)系管理員刪除。
轉(zhuǎn)載請(qǐng)注明本文地址:http://specialneedsforspecialkids.com/yun/72240.html
摘要:循環(huán)隊(duì)列是一種線性數(shù)據(jù)結(jié)構(gòu),其操作表現(xiàn)基于先進(jìn)先出原則并且隊(duì)尾被連接在隊(duì)首之后以形成一個(gè)循環(huán)。它也被稱為環(huán)形緩沖器。但是使用循環(huán)隊(duì)列,我們能使用這些空間去存儲(chǔ)新的值。檢查循環(huán)隊(duì)列是否已滿。 設(shè)計(jì)你的循環(huán)隊(duì)列實(shí)現(xiàn)。 循環(huán)隊(duì)列是一種線性數(shù)據(jù)結(jié)構(gòu),其操作表現(xiàn)基于 FIFO(先進(jìn)先出)原則并且隊(duì)尾被連接在隊(duì)首之后以形成一個(gè)循環(huán)。它也被稱為環(huán)形緩沖器。循環(huán)隊(duì)列的一個(gè)好處是我們可以利用這個(gè)隊(duì)列之前...
摘要:刪除操作也被稱為出隊(duì)。如上所述,隊(duì)列應(yīng)支持兩種操作入隊(duì)和出隊(duì)。循環(huán)隊(duì)列此前,我們提供了一種簡(jiǎn)單但低效的隊(duì)列實(shí)現(xiàn)。更有效的方法是使用循環(huán)隊(duì)列。它也被稱為環(huán)形緩沖器。檢查循環(huán)隊(duì)列是否已滿。表示隊(duì)列的起始位置,表示隊(duì)列的結(jié)束位置。 LeetCode 622:設(shè)計(jì)循環(huán)隊(duì)列 Design Circular Queue 首先來(lái)看看隊(duì)列這種數(shù)據(jù)結(jié)構(gòu): 隊(duì)列:先入先出的數(shù)據(jù)結(jié)構(gòu) showImg(ht...
Problem Convert a BST to a sorted circular doubly-linked list in-place. Think of the left and right pointers as synonymous to the previous and next pointers in a doubly-linked list. Lets take the foll...
Problem Given an array of integers with possible duplicates, randomly output the index of a given target number. You can assume that the given target number must exist in the array. Note:The array siz...
摘要:小鹿題目設(shè)計(jì)實(shí)現(xiàn)雙端隊(duì)列。你的實(shí)現(xiàn)需要支持以下操作構(gòu)造函數(shù)雙端隊(duì)列的大小為。獲得雙端隊(duì)列的最后一個(gè)元素。檢查雙端隊(duì)列是否為空。數(shù)組頭部刪除第一個(gè)數(shù)據(jù)。以上數(shù)組提供的使得更方便的對(duì)數(shù)組進(jìn)行操作和模擬其他數(shù)據(jù)結(jié)構(gòu)的操作,棧隊(duì)列等。 Time:2019/4/15Title: Design Circular DequeDifficulty: MediumAuthor: 小鹿 題目:Desi...
閱讀 2742·2021-11-24 10:23
閱讀 1153·2021-11-17 09:33
閱讀 2503·2021-09-28 09:41
閱讀 1409·2021-09-22 15:55
閱讀 3641·2019-08-29 16:32
閱讀 1903·2019-08-29 16:25
閱讀 1056·2019-08-29 11:06
閱讀 3421·2019-08-29 10:55