leetcode104二叉树搜索

1. 深度优先搜索，递归

maxDepth(TreeNode* root){
  if(!root)return 0;
  return max(maxDepth(root->left),maxDepth(root->right))+1;    
}

1. 广度优先搜索，队列

queue<TreeNode*>q;
q.push(root);
while(!q.empty()){
  int size=q.size();
  while(size>0){
     TreeNode* node=q.front();q.pop();
      if(node->left)q.push(node->left);
      if(node->right)q.push(node->right);  
      size--;
  }
  //一层遍历结束
  ans++;       
}