xinyu04

摘要： You are given a 2D array of integers `envelopes` where `envelopes[i] = [wi, hi]` represents the width and the height of an envelope. One envelope can 阅读全文

摘要： There is an `m x n` binary grid matrix with all the values set 0 initially. Design an algorithm to randomly pick an index `(i, j)` where `matrix[i][j] 阅读全文