NC248:左叶子之和(C++)

/**
 * struct TreeNode {
 *  int val;
 *  struct TreeNode *left;
 *  struct TreeNode *right;
 *  TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 * };
 */
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param root TreeNode类 
     * @return int整型
     */
    int count=0;
    int sumOfLeftLeaves(TreeNode* root) {
        if(root==nullptr)
            return 0;
        TreeNode* leftnode=root->left;
        if(leftnode&&!leftnode->left&&!leftnode->right)
        {
            count +=leftnode->val;
            sumOfLeftLeaves(root->right);
        }
        else {
        {
            sumOfLeftLeaves(root->left);
            sumOfLeftLeaves(root->right);
        }
        }
        return count;
    }
};