題目描述

從上到下按層列印二叉樹，同一層結點從左至右輸出。每一層輸出一行。

程式碼實現

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};
*/
class Solution {
public:
        vector<vector<int> > Print(TreeNode* pRoot) {
            vector
 
<vector<int> > vec;
            if(pRoot == NULL) return vec;

            queue<TreeNode*> q;
            q.push(pRoot);

            while(!q.empty())
            {
                int lo = 0, hi = q.size();
                vector<int> c;
                while(lo++ < hi)
                {
                    TreeNode *t = q.front();
                    q.pop();
                    c.push_back(t->val);
                    if
 
(t->left) q.push(t->left);
                    if(t->right) q.push(t->right);
                }
                vec.push_back(c);
            }
            return vec;
        }
};