SOURCE

const tree = [5, 8, 9, null, null, 7, 6, null, null, null, null, 3, 2, 4, 5]

function getMinValue(tree) {
    let minValuePath = []
    function getTree(index, path) {
        if (tree[index] == null) {
            return
        }
        path.push(tree[index])
        if(index === 1 ||tree[index] < minValuePath[minValuePath.length-1]){
            minValuePath = path
        }
        getTree(2 * index + 1, [...path])
        getTree(2 * index + 2, [...path])
    }
    getTree(0, [])
    return minValuePath
}

console.log(getMinValue(tree))