medium iter-prac btree.js

// 9, 12, 14, 17, 19, 23, 50, 72, 54, 67, 76
const nine = {value: 9, left: null, right: null};
const fourteen = {value: 14, left: null, right: null};
const twelve = {value: 12, left: nine, right: fourteen};
const nineteen = {value: 19, left: null, right: null};
const twentythree = {value: 23, left: nineteen, right: null};
const seventeen = {value: 17, left: twelve, right: nineteen};

const sixtyseven = {value: 67, left: null, right: null};
const fiftyfour = {value: 54, left: null, right: sixtyseven};
const seventysix = {value: 76, left: null, right: null};
const seventytwo = {value: 72, left: fiftyfour, right: seventysix};
const fifty = {value: 9, left: seventeen, right: seventytwo};