# LeetCode 216. Combination Sum III

Description https://leetcode.com/problems/combination-sum-iii/ Find all valid combinations of k numbers that sum up to n such that the following conditions are true: Only numbers 1 through 9 are used.…

# LeetCode 526. Beautiful Arrangement

Description https://leetcode.com/problems/beautiful-arrangement/ Suppose you have n integers labeled 1 through n. A permutation of those n integers perm (1-indexed) is considered a beautiful arrangement if for every i (1 <= i <= n), either of…

# LeetCode 784. Letter Case Permutation

Description https://leetcode.com/problems/letter-case-permutation/ Given a string s, we can transform every letter individually to be lowercase or uppercase to create another string.…

# LeetCode 47. Permutations II

Description https://leetcode.com/problems/permutations-ii/ Given a collection of numbers, nums, that might contain duplicates, return all possible unique permutations in any order. Example 1: Input: nums…

# LeetCode 77. Combinations

Description https://leetcode.com/problems/combinations/ Given two integers n and k, return all possible combinations of k numbers out of the range [1, n]. You may return the answer in any…

# LeetCode 1641. Count Sorted Vowel Strings

Description https://leetcode.com/problems/count-sorted-vowel-strings/ Given an integer n, return the number of strings of length n that consist only of vowels (a, e, i, o, u) and are lexicographically sorted. A…

# LeetCode 1863. Sum of All Subset XOR Totals

Description https://leetcode.com/problems/sum-of-all-subset-xor-totals/ The XOR total of an array is defined as the bitwise XOR of all its elements, or 0 if the array is empty. For example, the XOR…

# LeetCode 351. Android Unlock Patterns

Description https://leetcode.com/problems/android-unlock-patterns/ Given an Android 3×3 key lock screen and two integers m and n, where 1 ≤ m ≤ n ≤ 9, count the…

# LeetCode 212. Word Search II

Description https://leetcode.com/problems/word-search-ii/ Given an m x n board of characters and a list of strings words, return all words on the board. Each word must…

# LeetCode 489. Robot Room Cleaner

Description https://leetcode.com/problems/robot-room-cleaner/ You are controlling a robot that is located somewhere in a room. The room is modeled as an m…