Sum Root to Leaf Numbers

最新推荐文章于 2024-08-27 16:38:35 发布

zephyr_be_brave

最新推荐文章于 2024-08-27 16:38:35 发布

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分类专栏： leetcode习题分析

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本文探讨如何计算给定二叉树中从根节点到叶子节点的所有路径所表示的数字之和。通过实例和代码实现，深入理解二叉树路径求和的算法逻辑。

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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.

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int sumNumbers(TreeNode *root) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if(root == NULL) return 0;
        return returnSum(0,root);
    }
    
    int returnSum(int root_val,TreeNode *root)
    {
        root_val+=root->val;
        if(root->left == NULL && root->right == NULL) return root_val;
        root_val *= 10;
       
        int ret = 0;
        
        if(root->left != NULL)
            ret += returnSum(root_val,root->left);
        if( root->right != NULL)
            ret += returnSum(root_val,root->right);
        
        return ret;
        
    }
};

16 milli secs