//Robin Coding Challenge!


//Write a function in JavaScript that accepts an array of integers and a number X as parameters, when invoked, returns an array of unique indices of two numbers whose sum is equal to X.

// For example: [1, 3, 4, 5, 6, 8, 10, 11, 13], Sum: 14

// Pairs of indices: [0, 8], [1, 7], [2, 6], [4, 5]



//define variables:
const numbers = [1, 3, 4, 5, 6, 8, 10, 11, 13]
const sum = 14

//Create function with two arguments (array, sum)
//Create variable to return independent index pairs

findSum = (array, x) => {
    var indexArr = []

//For loop, iterating over all numbers in the set, searching for the difference between X (sum) and value at each index
//Lists indices of numbers whose sums total X, pushes to empty array

    for(let i = 0; i <= array.length; i++) {
        var map = array[i]
        var diff = (x - map)
        var index = array.indexOf(diff)
        var answer = [i, index]
            if (index > i) {
                indexArr.push(answer)
            }
    } return indexArr
}
    console.log(findSum(numbers, sum));


    //This solution is a bit blunt force, with the discriminating if statement working because each array value is sequential
    //I would refactor to discriminate between index values and that were already listed, even if the number set given was not sequential
   //I might also consider using .reduce() with the list of indices as an accumulator
   //I would love to hear your notes on this, thank you for your consideration! -Chris