N叉树问题

LeetCode589. N 叉树的前序遍历

class Solution {
public:
	vectorres;
    vector preorder(Node* root) {
	 	if(!root) return {};
        res.push_back(root->val);
	 	for(auto p:root->children){
    		preorder(p);
		}
		return res;
    }
};

LeetCode589. N 叉树的后序遍历

class Solution {
public:
	vectorres; 
    vector postorder(Node* root) {
		if(!root) return {};
		for(auto p:root->children){
			postorder(p);
		}
		res.push_back(root->val);
		return res;
    }
};

LeetCode429. N 叉树的层序遍历

class Solution {
public:
	queueque;
	vector>ans;
	vector level_ans;
    vector> levelOrder(Node* root) {
    	if(root==NULL) return {}; 	
		que.push(root);
		while(!que.empty()){
			int size=que.size(); 
			vectorvec;
			for(int i=0;i
				Node* node=que.front();
				que.pop();
				if(node!=NULL){
					vec.push_back(node->val);
					for(auto v:node->children){
						que.push(v);
					}
				}
			}
			ans.push_back(vec);	
		}
		return ans;
    }
};

LeetCode559. N 叉树的最大深度

class Solution {
public:
    int maxDepth(Node* root) {
    	if(root==NULL) return 0;
    	int d=0;
		for(auto v:root->children){
			d=max(d,maxDepth(v));
		}
		return d+1; 
    }
};