【树】leetcode_404_左叶子之和

【树】leetcode_404_左叶子之和

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    int sumOfLeftLeaves(TreeNode* root) {
        if (root == nullptr) return 0;
        
        int le = sumOfLeftLeaves(root->left);
        int ri = sumOfLeftLeaves(root->right);
        int left_leave_val = 0;
        if(root->left!= nullptr &&root->left->left==nullptr&& root->left->right==nullptr){
            left_leave_val = root->left->val;
        }

        return le+ri+left_leave_val;

    }
};