Binary Tree Depth

btree-depth.js

const getBTreeDepth = (tree) => {
    const isEmpty = arr => arr.every(item => item === -1)
    
    let nodes = 1;
    let depth = 0;

    let start = 0;
    let end = 1;

    while (nodes <= tree.length) {
        const clone = tree.slice(start, end);
        if (! clone.length || isEmpty(clone)) {
            break;
        }

        depth++;        
        nodes *= 2;

        start = end;
        end = end + nodes;
    }

    return depth;
};

console.assert( getBTreeDepth([0]) === 1  )
console.assert( getBTreeDepth([0, 2, 3 ]) === 2 )
console.assert( getBTreeDepth([0, 1, 2, -1, -1, -1, -1]) === 2  )
console.assert( getBTreeDepth([0, 1, 2, 1, -1, -1, -1, 1,2,3,4,5,6,7,8,1]) === 5  )