Leetcode 225: Implement Stack using Queues
Question
Implement the following operations of a stack using queues.
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Leetcode 220: Contains Duplicate III
Question Given an array of integers, find out whether there are two distinct indices i and j in the array such that the absolute difference between nums[i] and nums[j] is at most t and the absolute difference between i and j is at most k. [Read More] -
Leetcode 219: Contains Duplicate II
Question Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most k. [Read More] -
Leetcode 216: Combination Sum III
Question Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique set of numbers. [Read More] -
Leetcode 211: Add and Search Word - Data structure design
Question Design a data structure that supports the following two operations: [Read More] -
Leetcode 215: Kth Largest Element in an Array
Question Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element. [Read More] -
Leetcode 209: Minimum Size Subarray Sum
Question Given an array of n positive integers and a positive integer s, find the minimal length of a contiguous subarray of which the sum ≥ s. If there isn’t one, return 0 instead. [Read More] -
Leetcode 208: Implement Trie (Prefix Tree)
Question Implement a trie with insert, search, and startsWith methods. [Read More] -
Leetcode 205: Isomorphic Strings
Question Given two strings s and t, determine if they are isomorphic. [Read More] -
Leetcode 204: Count Primes
Question Count the number of prime numbers less than a non-negative number, n. [Read More] -
Leetcode 202: Happy Number
Question Write an algorithm to determine if a number is “happy”. [Read More] -
Leetcode 201: Bitwise AND of Numbers Range
Question Given a range [m, n] where 0 <= m <= n <= 2147483647, return the bitwise AND of all numbers in this range, inclusive. [Read More] -
Leetcode 186: Reverse Words in a String II
Question Given an input string , reverse the string word by word. [Read More] -
Leetcode 187: Repeated DNA Sequences
Question All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T, for example: “ACGAATTCCG”. When studying DNA, it is sometimes useful to identify repeated sequences within the DNA. [Read More] -
Leetcode 189: Rotate Array
Question Given an array, rotate the array to the right by k steps, where k is non-negative. [Read More]