今天在复习Arrays and String 时看到一个很有趣的问题.希望跟大家分享一下. Implement the hash table using array / binary search tree 1.  Using Array/LinkedList: 1) key需要通过hash 来得到array中的index 2) array的每一位都是放着一个list 3) 需要自己定义一个class,list 由这个class 类型组成 4) 要考虑到万一hashvalue 范围很大,需要把t…

LeetCode 33 Search in Rotated Sorted Array [binary search] <c++> 给出排序好的一维无重复元素的数组,随机取一个位置断开,把前半部分接到后半部分后面,得到一个新数组,在新数组中查找给定数的下标,如果没有,返回-1.时间复杂度限制\(O(log_2n)\) C++ 我的想法是先找到数组中最大值的位置.然后以此位置将数组一分为二,然后在左右两部分分别寻找target. 二分寻找最大值的时候,因为左半部分的数一定大于nums[l],所以n…

Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times. You may assume that the array is non-empty and the majority element always exist in the array. Moore voting algorithm--每找出两…

Binary Search T(n) = T(n/2) + O(1)   =>    T(n) = O(lg n) proof: 如果能用iterable , 就用while loop, 可以防止用recursion的时候stack overflow( process in Linux is 8Mb), stack room is static for each process. (堆空间, heap room 是内存, 是动态的.)层数越多,存储更多中间/临时变量,最终超过系统配的stack空…

Binary Search algorithm. Wikipedia definition: In computer science, binary search, also known as half-interval search, logarithmic search, or binary chop, is a search algorithm that finds the position of a target value within a sorted array. Binary s…

Description Given a sorted array of n integers, find the starting and ending position of a given target value. If the target is not found in the array, return [-1, -1]. Example Given [5, 7, 7, 8, 8, 10] and target value 8,return [3, 4]. Challenge O(l…

原题链接在这里:https://leetcode.com/problems/check-if-a-number-is-majority-element-in-a-sorted-array/ 题目: Given an array nums sorted in non-decreasing order, and a number target, return True if and only if target is a majority element. A majority element is…

We all know how to search through an array for an element whose value equals the target value, but how to search for the element that has value greater than the target value? A particularly elegant way of thinking about this problem is to think about…

Given an array where elements are sorted in ascending order, convert it to a height balanced BST. 这道题是要将有序数组转为二叉搜索树,所谓二叉搜索树,是一种始终满足左<根<右的特性,如果将二叉搜索树按中序遍历的话,得到的就是一个有序数组了.那么反过来,我们可以得知,根节点应该是有序数组的中间点,从中间点分开为左右两个有序数组,在分别找出其中间点作为原中间点的左右两个子节点,这不就是是二分查找法的核…

Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times. You may assume that the array is non-empty and the majority element always exist in the array. public class Solution { //更好…