Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand. (i.e., [0,1,2,4,5,6,7] might become [4,5,6,7,0,1,2]). You are given a target value to search. If found in the array return its index, otherwise return -1.…

Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand. (i.e.,  [0,1,2,4,5,6,7] might become  [4,5,6,7,0,1,2]). Find the minimum element. You may assume no duplicate exists in the array. Example 1: Input: [3,4,5…

LeetCode 81 Search in Rotated Sorted Array II [binary search] <c++> 给出排序好的一维有重复元素的数组,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是否存在,时间复杂度限制\(O(log_2n)\) C++ 因为有重复元素存在,nums[l] <= nums[mid]不能说明[l,mid]区间内一定是单调的,比如数组[1,2,3,1,1,1,1],但是严格小于和严格大于的情况还是可以…

这4个题都是针对旋转的排序数组.其中153.154是在旋转的排序数组中找最小值,33.81是在旋转的排序数组中找一个固定的值.且153和33都是没有重复数值的数组,154.81都是针对各自问题的版本1增加了有重复数值的限制条件. 153.154都需要考虑是否旋转成和原数组一样的情况,特别的,154题还需要考虑10111和11101这种特殊情况无法使用二分查找. 33.81则不用考虑这些情况. 找最小值的题主要是利用最小值小于他前一个位置的数,同时也小于后一个位置的数 153. Find Mini…

LeetCode:Convert Sorted Array to Binary Search Tree Given an array where elements are sorted in ascending order, convert it to a height balanced BST 分析:找到数组的中间数据作为根节点,小于中间数据的数组来构造作为左子树,大于中间数据的数组来构造右子树,递归解法如下 /** * Definition for binary tree * struct…

Convert Sorted Array to Binary Search Tree Given an array where elements are sorted in ascending order, convert it to a height balanced BST. 很简单的二分法,只要给出Array的开始和结束下标作为参数传入即可. public TreeNode sortedArrayToBST(int[] num) { return constructBST(num,0,nu…

Convert Sorted List to Binary Search Tree OJ: https://oj.leetcode.com/problems/convert-sorted-list-to-binary-search-tree/ Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST. 思想: 以中间点为根节点,按先序顺序…

Convert Sorted List to Binary Search Tree Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST. 本来想在递归中不用for循环把问题解决点,想了很久不知道该怎么做,看了网上的答案,发现大家就是用的循环····· 用循环的话,就非常简单了,但是我写代码的时候,子函数用引用传参数的时候报错,不知道…

https://leetcode.com/problems/find-minimum-in-rotated-sorted-array-ii/description/ -- leetcode follow up question: find the minimum element in a rotated array with duplicate elements Idea: [3,3,1,3] compared to [3,4,1,2]  -> l = mid+1 --1 [1,3,3] com…

We are playing the Guess Game. The game is as follows: I pick a number from 1 to n. You have to guess which number I picked. Every time you guess wrong, I'll tell you whether the number is higher or lower. You call a pre-defined API guess(int num) wh…