Opium_Z的博客

Problem:Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.Input: [1,2,3,null,5,null,4]Output: [1, 3, 4]E...

problem:Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. A mapping of digit to letters is just like on the telephone butto...

Problem:A message containing letters from A-Z is being encoded to numbers using the following mapping:‘A’ -> 1‘B’ -> 2…‘Z’ -> 26Given a non-empty string containing only digits, determin...

Problem:Analysisscan grid to find ‘1’if ‘1’, then dfs or bfs and labelCodeclass Solution1 { // 1. scan grid 2.if ==1, dfs and label final static int[][] dirs = {{1,0},{-1,0},{0,1},...

ProblemGive a string, like “abc”, return all the possible combinations (all the chars are different)example:input: “abc”output: [abc, acb, bac, bca, cab, cba]Analysisobviously, this problem can ...

Problem:Analysis:In this problem, I gonna use DFS to solve it. By using recursion, we should set up the base rule and recursive rule.there is a small trick in this problem, we should pass the int[...