摘要： Problem： Given two strings s1, s2, find the lowest ASCII sum of deleted characters to make two strings equal. Example 1: Example 2: 给定两个字符串s1,s2，删除其中一 阅读全文

摘要： Problem： A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below). The robot can only move either down or right 阅读全文

摘要： Problem: Given two non-empty binary trees s and t, check whether tree t has exactly the same structure and node values with a subtree of s. A subtree 阅读全文