A supermarket offers various products, each with an associated price. The customers make purchases where the subtotal is calculated based on the prices and quantities of the products they buy. Every nth customer gets a discount on their subtotal, and the final bill is calculated accordingly.
Given a string s consisting only of characters ‘a’, ‘b’, and ‘c’, your task is to find the number of substrings that contain at least one occurrence of each of the characters ‘a’, ‘b’, and ‘c’.
You are given n nodes in a binary tree, numbered from 0 to n-1. Each node i has two children: leftChild[i] and rightChild[i]. If a node has no left child, its value will be -1. Similarly, if a node has no right child, its value will also be -1. Your task is to return true if and only if these nodes form exactly one valid binary tree.
Given an integer num, find the closest two integers whose product is equal to either num + 1 or num + 2 and whose absolute difference is the smallest. You need to return these two integers in any order.
In a special ranking system, each voter assigns a rank to all participating teams in a competition. The rankings are based on the most first-place votes, then second-place votes, and so on. If there is still a tie, teams are ranked alphabetically.
You are given a binary tree and a linked list. Determine if there exists a downward path in the binary tree that matches all elements of the linked list starting from its head node. A downward path means starting from any node in the binary tree and following child nodes downwards.