class Tree {
  constructor(value = 0){
    this.value = value;
    this.visited = false;
    this.left = null;
    this.right = null;
    this.parent = null;
  }
}

// Let's construct a test case with the edge
// case of having identical sums

var root = new Tree(10);
var left = new Tree(5);
left.parent = root;
var right = new Tree(16);
right.parent = root;
var leftleft = new Tree(3);
leftleft.parent = left;
var leftright = new Tree(8);
leftright.parent = left;

var rightleft = new Tree(11);
rightleft.parent = right;
right.left = rightleft;

root.left = left;
root.right = right;
left.left = leftleft;
left.right = leftright;


var largestSum = (tree, level) => {
  var sums = [];

  function findSums(tree, currentLevel, currentTotal){
    // if (tree.visited === true
    //       && tree.left !== null && tree.left.visited === true
    //       && tree.right !== null && tree.right.visited === true){
    //   if (tree.parent !== null){
    //     findSums(tree.parent, currentLevel - 1, currentTotal - tree.value);
    //   }
    // }

    console.log('visiting', tree);

    tree.visited = true;
    var newTotal = tree.value + currentTotal;

    if (tree.parent === null
          && (tree.left === null || tree.left.visited === true)
          && (tree.right === null || tree.right.visited === true)
          ){
      return;
    }

    if (currentLevel === level){
      sums.push(newTotal);
      // go back up the tree
      if (tree.parent !== null){
        return findSums(tree.parent, currentLevel - 1, newTotal - tree.value - tree.parent.value);
      }
    }

    if (tree.left === null && tree.right === null){
      if (tree.parent !== null){
        findSums(tree.parent, currentLevel - 1, newTotal - tree.value - tree.parent.value);
      } else {
        return;
      }
    } else {
      if (tree.left !== null && tree.left.visited === false){
        findSums(tree.left, currentLevel + 1, newTotal);
      }

      if (tree.right !== null && tree.right.visited === false){
        findSums(tree.right, currentLevel + 1, newTotal);
      }

      // else if (tree.parent !== null){
      //   findSums(tree.parent, currentLevel - 1, newTotal - tree.value - tree.parent.value);
      // }
    }
  }


  // find sums
  findSums(tree, 0, 0);
  return Math.max.apply(null, sums);
}