Given a triangle array, return the minimum path sum from top to bottom. For each step, you may move to an adjacent number of the row below. More formally, if you are on index i on the current row, you may move to either…
Given an integer rowIndex, return the rowIndexth (0-indexed) row of the Pascal's triangle. In Pascal's triangle, each number is the sum of the two numbers directly above it as shown: Example 1: Example 2: Example 3…
Given an integer numRows, return the first numRows of Pascal's triangle. In Pascal's triangle, each number is the sum of the two numbers directly above it as shown: Example 1: Example 2: Constraints: 1 <= numRows <= 30…
Given the head of a sorted linked list, delete all duplicates such that each element appears only once. Return the linked list sorted as well. Example 1: Example 2: Constraints: The number of nodes in the list is in the…
Given an m x n grid of characters board and a string word, return true if word exists in the grid. The word can be constructed from letters of sequentially adjacent cells, where adjacent cells are horizontally or…
Given an integer array nums of unique elements, return all possible subsets (the power set). The solution set must not contain duplicate subsets. Return the solution in any order. Example 1: Example 2: Constraints: 1 <=…
Given an array nums with n objects colored red, white, or blue, sort them in-place so that objects of the same color are adjacent, with the colors in the order red, white, and blue. We will use the integers 0, 1, and 2…
You are climbing a staircase. It takes n steps to reach the top. Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top? Example 1: Example 2: Constraints: 1 <= n <= 45 Solution…
Given a non-negative integer x, compute and return the square root of x. Since the return type is an integer, the decimal digits are truncated, and only the integer part of the result is returned. Example 1: Example 2…
Given a non-empty array of decimal digits representing a non-negative integer, increment one to the integer. The digits are stored such that the most significant digit is at the head of the list, and each element in the…
Given an array of strings strs, group the anagrams together. You can return the answer in any order. An Anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all…
Given two non-negative integers num1 and num2 represented as strings, return the product of num1 and num2, also represented as a string. Note: You must not use any built-in BigInteger library or convert the inputs to…
Determine if a 9 x 9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules: Each row must contain the digits 1-9 without repetition. Each column must contain the digits 1-9…
Implement strStr(). Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. Clarification: What should we return when needle is an empty string? This is a great question…
Given an array nums and a value val, remove all instances of that value in-place and return the new length. Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1)…
Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if: Open brackets must be closed by the same type of brackets. Open…
Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. Return the answer in any order. A mapping of digit to letters (just like on the telephone…
Write a function to find the longest common prefix string amongst an array of strings. If there is no common prefix, return an empty string "". Example 1: Example 2: Constraints: 0 <= strs.length <= 200 0 <=…
The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility) And then read line by line: "PAHNAPLSIIGYIR"…
Given alphanumeric string s. (Alphanumeric string is a string consisting of lowercase English letters and digits). You have to find a permutation of the string where no letter is followed by another letter and no digit…