[leetcode]Binary Tree Level Order Traversal

 

#include <iostream>
#include <vector>
#include <stack>
#include <queue>
using namespace std;


struct TreeNode {
    int val;
    TreeNode *left;
    TreeNode *right;
    TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};

class Solution {
public:
    vector<vector<int> > levelOrder(TreeNode *root) {
        result.clear();
        if (!root)
            return result;

        queue<TreeNode *> q;//层序遍历需要一个queue
        q.push(root);

        queue<TreeNode *> tmpQ;//因为每一层要分开，所以另开辟一个queue缓存一层
        while(!q.empty()){
            while(!q.empty()){
                tmpQ.push(q.front());
                q.pop();
            }
            
            vector<int> oneLevel;
            while(!tmpQ.empty()){
                oneLevel.push_back(tmpQ.front()->val);//对于该层全部遍历
                if (tmpQ.front()->left)
                    q.push(tmpQ.front()->left);
                if (tmpQ.front()->right)
                    q.push(tmpQ.front()->right);
                tmpQ.pop();
            }

            result.push_back(oneLevel);
        }

        return result;
    }
private:
    vector<vector<int> > result;//!!
};


int main()
{
    
    return 0;
}

 

 

 

 

 

EOF