BFS

Hi, everyone! Today, we’ll be looking at LeetCode problem 399. In this problem, we are given a bunch of reference equations of the form \(a_i / b_i = c_i\) for \(i = 1 , \dots, n\). The symbols \(a_i, b_i\) are given as strings, while \(c_i\) are given as floating point numbers. We’re then asked to compute the value of a query equation \(q_1 / q_2\). If \(q_1 / q_2\) is one of the reference equations, we can return that value. Otherwise, we can follow a kind of chain-rule strategy. Suppose we are given "a" / "b" with value 2.0 and "b" / "c" with value 3.0, then we can compute "a" / "c" by the product: "a" / "c" = "a" / "b" * "b" / "c", which is equal to 2.0 * 3.0 = 6.0. If there’s no way to find a solution, we return -1. ...