LeetCode: Maximum Depth of Binary Tree in Objective C typedef struct { int value; struct TreeNode *left; struct TreeNode *right; } TreeNode; - (int)maximumDepth:(TreeNode *)node { if (!node) return 0;

typedef struct { int value; struct TreeNode *left; struct TreeNode *right; } TreeNode; -(NSMutableArray *)levelOrder:(TreeNode *)treeNode { NSMutableArray *levelOrderArray = [NSMutableArray array]; if

// typedef struct { // int value; // struct TreeNode *left; // struct TreeNode *right; // } TreeNode; -(NSMutableArray *)preorderTraversal:(TreeNode *)treeNode { NSMutableArray *preorderArray = [NSMutableArray