Evaluate Division

Problem statement

You are given an array of variable pairs equations and an array of real numbers values, where 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 are also given some queries, where queries[j] = [Cj, Dj] represents the jth query where you must find the answer for Cj / Dj = ?.

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

Note: The input is always valid. You may assume that evaluating the queries will not result in division by zero and that there is no contradiction.

Example 1:

Input: equations = [["a","b"],["b","c"]], values = [2.0,3.0], queries = [["a","c"],["b","a"],["a","e"],["a","a"],["x","x"]]Output: [6.00000,0.50000,-1.00000,1.00000,-1.00000]Explanation: Given: a / b = 2.0, b / c = 3.0queries are: a / c = ?, b / a = ?, a / e = ?, a / a = ?, x / x = ?return: [6.0, 0.5, -1.0, 1.0, -1.0 ]

Example 2:

Input: equations = [["a","b"],["b","c"],["bc","cd"]], values = [1.5,2.5,5.0], queries = [["a","c"],["c","b"],["bc","cd"],["cd","bc"]]Output: [3.75000,0.40000,5.00000,0.20000]

Example 3:

Input: equations = [["a","b"]], values = [0.5], queries = [["a","b"],["b","a"],["a","c"],["x","y"]]Output: [0.50000,2.00000,-1.00000,-1.00000]

Constraints:

• 1 <= equations.length <= 20
• equations[i].length == 2
• 1 <= Ai.length, Bi.length <= 5
• values.length == equations.length
• 0.0 < values[i] <= 20.0
• 1 <= queries.length <= 20
• queries[i].length == 2
• 1 <= Cj.length, Dj.length <= 5
• Ai, Bi, Cj, Dj consist of lower case English letters and digits.

My solution

/**
 * @param {string[][]} equations
 * @param {number[]} values
 * @param {string[][]} queries
 * @return {number[]}
 */
var calcEquation = function(equations, values, queries) {
    const valueMap = new Map();
    
    let i = 0;
    for (const [A, B] of equations) {
        const value = values[i]
        if (!valueMap.get(A)) {
            valueMap.set(A, [])
        }
        valueMap.get(A).push([B, value])
        
        if (!valueMap.get(B)) {
            valueMap.set(B, [])
        }
        valueMap.get(B).push([A, 1 / value])
        
        
        i++;
    }
    
    const result = [];
    
    for (const [start, destination] of queries) {
        if (!valueMap.has(start)) {
            result.push(-1)
        } else if (start === destination) {
            result.push(1)
        } else {
            const visited = new Set();
            const queue = [];
            
            queue.push([start, 1]);
            visited.add(start)
            let found = false;
            
            while (queue.length) {
                const [currVar, currValue] = queue.shift();                
                
                if (currVar === destination) {
                    result.push(currValue);
                    found = true;
                    break;
                }
                
                // console.log(currVar, currValue)
                
                if (!valueMap.has(currVar)) {
                    continue
                }
                
                for (const [nextVar, nextValue] of valueMap.get(currVar)) {
                    if (!visited.has(nextVar)) {
                        visited.add(nextVar)
                        
                        queue.push([nextVar, currValue * nextValue]);
                    }                    
                }
            }
            
            if (!found) {
                result.push(-1);
            }
        }
    }
    
    return result;
};