LeetCode 111 二叉树的最小深度

后序遍历

class Solution {
public:
    int dfs(TreeNode* node) {
        if (node == nullptr) return 0;

        if (node->left == nullptr && node->right != nullptr) {
            return 1 + dfs(node->right);
        }

        if (node->right == nullptr && node->left != nullptr) {
            return 1 + dfs(node->left);
        }

        return 1 + min(dfs(node->left), dfs(node->right)); 
    }
    int minDepth(TreeNode* root) {
        return dfs(root);
    }
};