摘要：
There are a number of spherical balloons spread in two-dimensional space. For each balloon, provided input is the start and end coordinates of the hor 阅读全文
摘要：
There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every 阅读全文
摘要：
Given a set of intervals, for each of the interval i, check if there exists an interval j whose start point is bigger than or equal to the end point o 阅读全文