刷题104. Maximum Depth of Binary Tree

一、题目说明

题目104. Maximum Depth of Binary Tree，求二叉树的最大高度。难度是Easy！

二、我的解答

按层遍历二叉树，就可以计算最大深度。下面是非递归算法：

class Solution{
	public:
		int maxDepth(TreeNode* root){
			queue<TreeNode*> q;
			TreeNode* p;
			if(root==NULL) return 0;
			q.push(root);
			int maxDep = 0;
			int curLevelNum = 1,nextLevelNum = 0;
			while(! q.empty()){
				for(int i=0;i<curLevelNum;i++){
					p = q.front();
					q.pop();
					
					if(p->left !=NULL){
						q.push(p->left);
						nextLevelNum++;
					}
					if(p->right !=NULL){
						q.push(p->right);
						nextLevelNum++;
					}
				}
				curLevelNum = nextLevelNum;
				nextLevelNum = 0;
				maxDep++;
			}
			return maxDep;
		}
};

性能如下：

Runtime: 8 ms, faster than 89.13% of C++ online submissions for Maximum Depth of Binary Tree.
Memory Usage: 19.3 MB, less than 79.12% of C++ online submissions for Maximum Depth of Binary Tree.

三、优化措施

Easy，就不优化了。