Backtracking

Return every root-to-leaf path in a binary tree as a list of node values, instead of an arrow-joined string.

Return every root-to-leaf path in a binary tree as an arrow-joined string.

A binary watch has 4 LEDs on the top to represent the hours (0-11), and 6 LEDs on the bottom to represent the minutes (0-59).

The XOR total of an array is defined as the bitwise XOR of all its elements, or 0 if the array is empty.

An additive number is a string whose digits can form an additive sequence.

Given a directed acyclic graph (DAG) of n nodes labeled from 0 to n - 1, find all possible paths from node 0 to node n - 1 and return them in any order.

We had some 2-dimensional coordinates, like "(1, 3)" or "(2, 0.5)".

Suppose you have n integers labeled 1 through n.

Given 2 integers n and start.

You would like to make dessert and are preparing to buy the ingredients.

Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where the chosen numbers sum to target.

Find all valid combinations of k numbers that sum up to n such that the following conditions are true: Return a list of all possible valid combinations.

Given two integers n and k, return all possible combinations of k numbers chosen from the range [1, n].

You are given a 0-indexed string pattern of length n consisting of the characters 'I' meaning increasing and 'D' meaning decreasing.

Given an integer n, find a sequence with elements in the range [1, n] that satisfies all of the following: The distance between two numbers on the sequence, a[i] and a[j], is the...

Given an integer array nums, find the maximum possible bitwise OR of a subset of nums and return the number of different non-empty subsets with the maximum bitwise OR.

Given an integer n, return the count of all numbers with unique digits, x, where 0 <= x < 10n.

You are given an integer array cookies, where cookies[i] denotes the number of cookies in the ith bag.

Given a positive integer n, return the punishment number of n.

Given an array of strings nums containing n unique binary strings each of length n, return a binary string of length n that does not appear in nums.

You are given a positive integer n.

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

An n-bit gray code sequence is a sequence of 2n integers where: Given an integer n, return any valid n-bit gray code sequence.

Given an array arr of 4 digits, find the latest 24-hour time that can be made using each digit exactly once.

Given a string s, you can transform every letter individually to be lowercase or uppercase to create another string.

Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent.

You have n tiles, where each tile has one letter tiles[i] printed on it.

You are given an integer array matchsticks where matchsticks[i] is the length of the ith matchstick.

There is a survey that consists of n questions where each question's answer is either 0 (no) or 1 (yes).

You are given an array of strings arr.

Alice and Bob are opponents in an archery competition.

Given a string s, find two disjoint palindromic subsequences of s such that the product of their lengths is maximized.

You are given an m x n binary matrix matrix and an integer numSelect.

You are given an integer finalSum.

You are given a 0-indexed integer array nums representing the score of students in an exam.

There are n tasks assigned to you.

Bob is stuck in a dungeon and must break n locks, each requiring some amount of energy to break.

An integer x is numerically balanced if for every digit d in the number x, there are exactly d occurrences of that digit in x.

Given an integer array nums, return all the different possible non-decreasing subsequences of the given array with at least two elements.

Given two integers n and k, return an array of all the integers of length n where the difference between every two consecutive digits is k.

Given a string s, partition s such that every substring of the partition is a palindrome.

Given a binary string s, partition the string into one or more substrings such that each substring is beautiful.

Given an integer array nums and an integer k, return true if it is possible to divide this array into k non-empty subsets whose sums are all equal.

In a gold mine grid of size m x n, each cell in this mine has an integer representing the amount of gold in that cell, 0 if it is empty.

Given an array nums of distinct integers, return all the possible permutations.

Given a collection of numbers, nums, that might contain duplicates, return all possible unique permutations in any order.

A valid IP address consists of exactly four integers separated by single dots.

In an online store, there are n items to sell.

Given a string s, return the maximum number of unique substrings that the given string can be split into.

You are given a string of digits num, such as "123456579".