摘要：A message containing letters from A-Z is being encoded to numbers using the following mapping: Given an encoded message containing digits, determine t 阅读全文

摘要：Given a collection of integers that might contain duplicates, nums, return all possible subsets. Note: The solution set must not contain duplicate sub 阅读全文

摘要：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 tha 阅读全文

摘要：The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other. Given an integer n, return all 阅读全文