摘要：
We are given S, a length n string of characters from the set {'D', 'I'}. (These letters stand for "decreasing" and "increasing".) A valid permutation 阅读全文
摘要：
In the video game Fallout 4, the quest "Road to Freedom" requires players to reach a metal dial called the "Freedom Trail Ring", and use the dial to s 阅读全文
摘要：
Given n balloons, indexed from 0 to n-1. Each balloon is painted with a number on it represented by array nums. You are asked to burst all the balloon 阅读全文