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Medium Level · Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. Symbol Value I 1 V 5 X ...

Given the root of a binary tree, find the maximum value v for which there exist different nodes a and b where v = |a.val - b.val| and a is an ancestor...

2385. Amount of Time for Binary Tree to Be Infected Medium 243458Add to ListShare You are given the root of a binary tree with unique values, and an...

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

backtracking problem solution · The n-queens puzzle is the problem of placing n queens on an n x n chessboard such that no two queens attack each...

a simple implementation in python · Solution def bfs(graph, visited): queue = [] queue.append("a") visited["a"] = True while queue: temp =...