摘要：
Given an integer n, generate all structurally unique BST's (binary search trees) that store values 1...n. （Medium） For example,Given n = 3, your progr 阅读全文
摘要：
Given a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing only 1's and return its area. （Hard） For example, given the fo 阅读全文