原题绿皮书 Ch2 Brain TeasersYou have two ropes, each of which takes 1 hour to burn. But either rope has different densities at different points, so theres no guarantee of consistency in the time it takes different sections within the rope to burn. How do you use these two ropes to measure 45 minutes?中文题意你有两根编子每根烧完恰好1小时但密度不均匀烧一半长度不等于过了半小时。如何精确测量45分钟解答核心洞察一根绳子两头同时点燃无论密度如何一定30分钟烧完。速度×2时间÷2。操作步骤t0绳A点熔两始绳B只点燃一端同时开始。t30min绳A烧完。立刻点燃绳B的另一端。t45min绳B烧完。剩余30min的量两头烧15min烧完。答案301545分钟。#量化面试 #Quant #BrainTeaser #逆向思维 #创造性思维