摘要：
You have a browser of one tab where you start on the homepage and you can visit another url, get back in the history number of steps or move forward i 阅读全文
摘要：
There are n cities connected by some number of flights. You are given an array flights where flights[i] = [fromi, toi, pricei] indicates that there is 阅读全文
摘要：
You are given a string s and an integer k. You can choose any character of the string and change it to any other uppercase English character. You can 阅读全文
摘要：
Given two sparse matrices mat1 of size m x k and mat2 of size k x n, return the result of mat1 x mat2. You may assume that multiplication is always po 阅读全文