const hasPathToSum = function(node, targetSum) {
  // your code here
  let rec = function(node, targetSum, currSum) {
  	if (node.value + currSum === targetSum) {
  		return true;
  	}
  	currSum += node.value;
	if (node.right && currSum + node.right.value <= targetSum) {
		return rec(node.right, targetSum, currSum);
	} else if (node.left) {
		return rec(node.left, targetSum, currSum);
	} else {
		return false;
	}
  }
  return rec(node, targetSum, 0);
};

let root = {
	value: 4,
	left: {
		value: 2,
		left: {
			value: -1
		},
		right: {
			value: 3
		}
	},
	right: {
		value: 8,
		left: {
			value: 5
		},
		right: {
			value: 9
		}
	}
};

hasPathToSum(root, 4);
hasPathToSum(root, 6);
hasPathToSum(root, 5);
hasPathToSum(root, 12);
hasPathToSum(root, 17);
hasPathToSum(root, 21);
hasPathToSum(root, 0);
hasPathToSum(root, -10);