题解 | #完全二叉树结点数#

/**
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};
*/
class Solution {
public:
    int getDepth(TreeNode* head) {
        if (!head) {
            return 0;
        }
        return max(getDepth(head->left), getDepth(head->right)) + 1;
    }
    
    int nodeNum(struct TreeNode* head) {
        if(!head) {
            return 0;
        }
        int leftDepth = getDepth(head->left);
        int rightDepth = getDepth(head->right);
        if (leftDepth == rightDepth) {
            return pow(2, leftDepth) + nodeNum(head->right);
        } else {
            return pow(2, rightDepth) + nodeNum(head->left);
            
        }

    }
};