// Function
const indicesOfGivenSum = (arr, x) => {
    // Isolate the length of the given array
    const len = arr.length
    // Isolate the given sum 'x'
    const givenSum = x;
    // Instantiate the output varable as an empty array in which to push the appropriate indices
    let output = [];
    // Iterate over each element of the array
    for (let i = 0; i < len; i++) {
        // Compare each element of the array to every other element of the array, starting with the index after the current index 'i'
        for (let j = i + 1; j < len; j++) {
            // Placeholder for the sum of the elements are the current indices
            let currentSum = arr[i] + arr[j];
            // Compare the current sum to the given sum
            if (currentSum === givenSum) {
                // If the sum of elements at the current indices equal the given sum, push those elements as a subarray into the output array
                output.push([i, j]);
            }
        }
    }
    // Return the output array of subarrays that hold the unique indices of two numbers whose sum is equal to the given sum 'x'
    return output;
}

// Set variables to test the function
const testArrOne = [1, 3, 4, 5, 6, 8, 10, 11, 13];
const givenSumOne = 14;
const testArrTwo = [10, 11, 12, 13, 14, 15, 16, 6, 11];
const givenSumTwo = 22;
const testArrThree = [1, 4, 13, 16, 7, 12, 34, 5];
const givenSumThree = 17;
const testArrFour = [54, 27, 3, 15, 71, 13, "The ultimate answer to life, the universe, and everything", 1, -12, -29];
const givenSumFour = 42;

// Test the function - I used Node.js, so I just run 'node <filename.js> from the command line to test the functionality
console.log("Expected output: [0, 8], [1, 7], [2, 6], [4, 5]\n")
console.log(indicesOfGivenSum(testArrOne, givenSumOne));
console.log("\nExpected output: [0, 2], [1, 8], [6, 7]\n")
console.log(indicesOfGivenSum(testArrTwo, givenSumTwo));
console.log("\nExpected output: [0, 3], [1, 2], [5, 7]\n")
console.log(indicesOfGivenSum(testArrThree, givenSumThree));
console.log("\nExpected output: [0, 8], [1, 3], [4, 9]\n")
console.log(indicesOfGivenSum(testArrFour, givenSumFour));