Find the sum of all left leaves in a given binary tree.
Example:
3
/ \
9 20
/ \
15 7
There are two left leaves in the binary tree, with values
9 and
15 respectively. Return
24.
我是看了答案才觉得其实明白了题意，答案也就出来了
求树里面，所有有左孩子，而左孩子没有孩子的这样的左孩子值的和
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* struct TreeNode *left;
* struct TreeNode *right;
* };
*/
int sumOfLeftLeaves(struct TreeNode* root) {
if(root==NULL){
return 0;
}
if(root->left!=NULL&&root->left->left==NULL&&root->left->right==NULL){
return root->left->val+sumOfLeftLeaves(root->right);
}
return sumOfLeftLeaves(root->left)+sumOfLeftLeaves(root->right);
}
