Given a target string and a set of characters, the problem is to find the minimal number of times the set of characters need to be used to form the target string, and return the order in which the characters are used
Given an array of integers and a range of elements that could be in the array, the problem is to find the number of ways to construct the array such that the array has exactly K distinct integers in it
Given an undirected tree, the problem is to find the sum of the distances between each pair of nodes in the tree, and return an array that contains the sum of distances between the node i and all other nodes, in the same order as the input
Given an array of 0s and 1s and an integer k, the problem is to find the minimum number of times a k-length sequence of bits need to be flipped (i.e. 0s to 1s or 1s to 0s) in order to obtain an array of all 1s
Find the minimum number of k-length bit flips to make an array of all 1s or kth smallest string of instructions to reach the bottom-right corner of a grid
