Algorithms - Recursion

flatten.js

function flatten(arr) {
    let result = [];

    // Iterate through elements in array
    for (let i = 0; i < arr.length; i++) {
        // Check if element is array
        if (Array.isArray(arr[i])) {
            // Recursive case - concat result with recursive function
            result = result.concat(flatten(arr[i]));
        } else {
            // If number push into result
            result.push(arr[i]);
        }
    }

    return result;
  
}

// flatten([1, 2, 3, [4, 5] ]) // [1, 2, 3, 4, 5]
// flatten([1, [2, [3, 4], [[5]]]]) // [1, 2, 3, 4, 5]
// flatten([[1],[2],[3]]) // [1,2,3]
// flatten([[[[1], [[[2]]], [[[[[[[3]]]]]]]]]]) // [1,2,3]