摘要：
Given two integers dividend and divisor, divide two integers without using multiplication, division and mod operator. Return the quotient after dividi 阅读全文
摘要：
Given two non-negative integers num1 and num2 represented as strings, return the product of num1 and num2, also represented as a string. Example 1: Ex 阅读全文
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Given a collection of numbers that might contain duplicates, return all possible unique permutations. Example: 题意： 打印全排列，注明了给定序列可含有重复元素 Solution1: Bac 阅读全文
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Backtracking is an algorithm for finding all solutions by exploring all potential candidates. If the solution candidate turns to be not a solution (or 阅读全文
摘要：
You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Note: You have to rotate the image in-place, which 阅读全文