Leetcode--Sum Root to Leaf Numbers

最新推荐文章于 2019-08-20 23:29:03 发布

yskyj

最新推荐文章于 2019-08-20 23:29:03 发布

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分类专栏： Leetcode 文章标签： leetcode Sum Root to Leaf Num

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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.

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思路：记忆深搜

保存从根节点到叶子节点的路径值，求出所有路径值得和

/**
 * 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 result=0;
    void function(TreeNode* root,vector<int> tmp)
    {
        if(root==NULL)
        {
            int sum=0;
            for(int i=0;i<tmp.size();i++)//根节点到叶子节点的路径值
                sum =sum*10+tmp[i];
                
            result +=sum;//将该路径值加到result中
        }
        else{
            vector<int> temp(tmp);
            temp.push_back(root->val);
            if(root->left==NULL&&root->right==NULL)
                function(root->left,temp);
            else if(root->left==NULL&&root->right!=NULL)
                function(root->right,temp);
            else if(root->left!=NULL&&root->right==NULL)
                function(root->left,temp);
            else
            {
                function(root->left,temp);
                function(root->right,temp);
            }
        }
    }
    int sumNumbers(TreeNode *root) {
        if(root==NULL)
            return 0;
        vector<int> tmp;
        function(root,tmp);
        return result;
    }
};