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  • leetcode 129. Sum Root to Leaf Numbers ----- java

    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.

    For example,

        1
       / 
      2   3
    

    The root-to-leaf path 1->2 represents the number 12.
    The root-to-leaf path 1->3 represents the number 13.

    Return the sum = 12 + 13 = 25.

    按照题目中的规则求出结果。

    使用队列很容易可以得到结果。

    /**
     * Definition for a binary tree node.
     * public class TreeNode {
     *     int val;
     *     TreeNode left;
     *     TreeNode right;
     *     TreeNode(int x) { val = x; }
     * }
     */
    public class Solution {
        public int sumNumbers(TreeNode root) {
            if( root == null )
                return 0;
            int result = 0;
            Queue queue = new LinkedList<TreeNode>();
            queue.add(root);
    
            while( !queue.isEmpty() ){
    
                int size = queue.size();
                for( int i = 0;i<size;i++){
                    TreeNode node = (TreeNode) queue.poll();
                    if( node.left != null ){
                        node.left.val = node.val*10+node.left.val;
                        queue.add(node.left);
                    }
                    if( node.right != null){
                        node.right.val = node.right.val+node.val*10;
                        queue.add(node.right);
                    }
                    if( node.left == null && node.right == null ){
                        result+=node.val;
                    }
                }
    
    
            }
    
            return result;
            
        }
    }
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  • 原文地址:https://www.cnblogs.com/xiaoba1203/p/6036197.html
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