描述
Find the sum of all left leaves in a given binary tree.
样例
3
/ \
9 20
/ \
15 7
There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24.
比较简单,递归遍历就可以了。
/**
* Definition of TreeNode:
* class TreeNode {
* public:
* int val;
* TreeNode *left, *right;
* TreeNode(int val) {
* this->val = val;
* this->left = this->right = NULL;
* }
* }
*/
class Solution {
public:
/**
* @param root: t
* @return: the sum of all left leaves
*/
int sumOfLeftLeaves(TreeNode * root) {
// Write your code here
if(root==NULL) return 0;
int sum=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;
}
};