source: https://leetcode.com/problems/reorder-routes-to-make-all-paths-lead-to-the-city-zero/description/ Reorder Routes to Make All Paths Lead to the City Zero There are n cities numbered from 0 to n – 1 and n – 1 roads such that there is only one way to travel between two different cities (this network form a tree). Last year, The ministry of transport decided to ...