129.Sum Root to Leaf Numbers

Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number.

An example is the root-to-leaf path 1->2->3 which represents the number 123.

Find the total sum of all root-to-leaf numbers.

Note: A leaf is a node with no children.

Example:

Input: [1,2,3]
    1
   / \
  2   3
Output: 25

Explanation:

The root-to-leaf path 1->2 represents the number 12. The root-to-leaf path 1->3 represents the number 13. Therefore, sum = 12 + 13 = 25.

Example 2:

Input: [4,9,0,5,1]
    4
   / \
  9   0
 / \
5   1
Output: 1026

Explanation:

The root-to-leaf path 4->9->5 represents the number 495.
The root-to-leaf path 4->9->1 represents the number 491.
The root-to-leaf path 4->0 represents the number 40.
Therefore, sum = 495 + 491 + 40 = 1026.

Analyze

递归解题

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
var sumNumbers = function(root) {
  const analyzeObj = { sum: 0 }
  if (!root) return analyzeObj.sum

  analyzeSum(root, '', analyzeObj)
  return analyzeObj.sum
};

var analyzeSum = function(node, str, analyzeObj) {
  if (!node) return
  if (!node.left && !node.right) {
    str += String(node.val)
    analyzeObj.sum = analyzeObj.sum + parseInt(str, 10)
    return
  }

  str += String(node.val)

  analyzeSum(node.left, str, analyzeObj)
  analyzeSum(node.right, str, analyzeObj)
}

Similar Title

113、257