DIY: Evaluate Division

Problem statement

You are given equations, an array of variable pairs, and values, an array of real numbers. equations[i] = [Ai, Bi] and values[i] represent the equation Ai / Bi = values[i]. Each Ai or Bi is a string that represents a single variable.

You also have some queries, where queries[j] = [Cj, Dj] represents the jth query, and you must find the answer for Cj / Dj = ?.

Return the answers to all queries. If a single answer cannot be determined, return -1.0.

Input

The following is an example input:

equations = {{"a","b"},["b","c"}}
values = {2.0,3.0}
queries = {{"a","c"},{"b","a"},{"a","e"},{"a","a"},{"x","x"}}

Output

The following is an example output:

{6.0, 0.5, -1.0, 1.0, -1.0}

Coding exercise

For this coding exercise, you need to implement the evaluate(equations, values, queries) function. The function will return the answers for every variable pair in the queries array.