Given a string which consists of lowercase or uppercase letters, find the length of the longest palindromes that can be built with those letters. This is c……
Given a string which contains only lowercase letters, remove duplicate letters so that every letter appear once and only once. You must make sure your result ……
Suppose you have a random list of people standing in a queue. Each person is described by a pair of integers (h, k), where h is the height of the person and k……
Find the sum of all left leaves in a given binary tree. Example: 3 / \ 9 20 / \ 15 7 There are two left leaves in the binary tree, wi……
Given an encoded string, return it's decoded string. The encoding rule is: k[encoded_string], where the encoded_string inside the square brackets is being ……
Given a string s and a string t, check if s is subsequence of t. You may assume that there is only lower case English letters in both s and t. t is potenti……
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 exis……
Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array. Note: You may assume that nums1 has enough space (size that ……
Given an unsorted integer array, find the first missing positive integer. For example, Given [1,2,0] return 3, and [3,4,-1,1] return 2. Your algorit……
Given a positive integer n and you can do operations as follow: If n is even, replace n with n/2. If n is odd, you can replace n with either n + 1 or n ……
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