Creates a binary tree from one dimensional array and checks the largest branch from the root recursively.

binary-tree-from-arrays.js

function getSolution(arr) {
    if (Array.isArray(arr)) {
        if (arr.length <= 1) {
            return '';
        } else {
            const left = getSumOfBranch(arr, 2);
            const right = getSumOfBranch(arr, 3);
            return (left === right) ? '' : ((left > right) ? 'Left' : 'Right')
        }
    } else {
        return '';
    }
}

function getSumOfBranch(arr, index) {
    if (index - 1 < arr.length) {
        if (arr[index - 1] === -1) {
            return 0;
        }
        return arr[index - 1]
            + getSumOfBranch(arr, index * 2)
            + getSumOfBranch(arr, index * 2 + 1);
    }
    return 0;
}

var testArray = [
    [[3, 6, 9, -1, 10], 'Left'],
    [[1, 4, 100, 5], 'Right'],
    [[1, 10, 5, 1, 0, 6], ''],
    [[1], ''],
    [[], ''],
];

testArray.map((arr, index) => {
    var testArr = arr[0];
    var solution = arr[1];
    var result = getSolution(testArr);

    var status = (solution === result) ? 'PASS' : 'FAIL'

    solution = (solution === '') ? "''" : solution;
    result = (result === '') ? "''" : result;

    console.log();
    console.log(`Test case ${index}: ${status}`);
    console.log(`Expected: ${solution}`);
    console.log(`Result: ${result}`);
    console.log();
});