On an N x N grid, each square grid[i][j] represents the elevation at that point (i,…

Power of Two Given an integer, write a function to determine if it is a power of two. 整除法 复杂度 时间 O(1) 空间 O(1) …

1. 题目 Given a string containing just the characters ‘(‘, ‘)’, ‘{‘, ‘…

  Given a pattern and a string str, find if str follows the same pattern. Examples: pattern = "abba", str…

  You have a lock in front of you with 4 circular wheels. Each wheel has 10 slots: '0', '1', '2', '3…

  Sometimes people repeat letters to represent extra feeling, such as “hello” -> “he…

题目描述 You are playing the following Bulls and Cows game with your friend: You write down a number and ask your …

题目描述 Given a range [m, n] where 0 <= m <= n <= 2147483647, return the bitwise AND of all numbers in t…

  Start from integer 1, remove any integer that contains 9 such as 9, 19, 29… So now, you will have…

  Given a non-empty 2D array grid of 0’s and 1’s, an island is a group of…

  Implement a MyCalendar class to store your events. A new event can be added if adding the eve…

1. 题目 Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which min…