404. Sum of Left Leaves
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原题链接:https://leetcode.com/problems/sum-of-left-leaves/
原题:
Find the sum of all left leaves in a given binary tree.
3 / \ 9 20 / \ 15 7There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24.
题意:
给你一棵二叉树,要求你把所有最底部的左叶子值加起来,输出结果。
注意点:
我本来以为只要是左叶子的值,就应该加起来
但是看一下例子,
这里的预期值是5。
也就是说2 ,1,3这几个值是不会加上的,所以你要求的是像图中值为5的叶子这样的没有子节点的叶子的值。只要注意这一点,就可以利用分治的思想来写题了。
AC代码:
/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public: int sumOfLeftLeaves(TreeNode* root) { int sum=0; if(root == NULL) return 0; if(root->left!=NULL&&root->left ->left==NULL&&root->left->right==NULL) sum += root->left->val; sum+=sumOfLeftLeaves(root->left); sum+=sumOfLeftLeaves(root->right); return sum; }};
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- 404. Sum of Left Leaves
- 404. Sum of Left Leaves
- 404. Sum of Left Leaves
- 404. Sum of Left Leaves
- 404. Sum of Left Leaves
- 404. Sum of Left Leaves
- 404. Sum of Left Leaves
- 404. Sum of Left Leaves
- 404. Sum of Left Leaves
- 404. Sum of Left Leaves*
- 404. Sum of Left Leaves
- 404. Sum of Left Leaves
- 404. Sum of Left Leaves
- 404. Sum of Left Leaves
- 404. Sum of Left Leaves
- 404. Sum of Left Leaves
- 404. Sum of Left Leaves
- 404. Sum of Left Leaves
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