『模板』题解 | #按之字形顺序打印二叉树#

/*
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> > res;
        if( nullptr==pRoot ) 
        {
            return res;
        }

        queue< TreeNode * > solve;
        solve.push( pRoot );
        int count=1;
        int tag=1;//表示正序
        while( !solve.empty() )
        {
            vector<int> temp;
            int countTemp=0;
            while( count-- )
            {
                TreeNode * Help=solve.front();
                solve.pop();
                temp.push_back( Help->val );
                if( nullptr!=Help->left )
                {
                    solve.push( Help->left );
                    ++countTemp;
                }
                if( nullptr!=Help->right )
                {
                    solve.push( Help->right );
                    ++countTemp;
                }
            }
            count=countTemp;

            if( -1==tag )
            {
                reverse( temp.begin(), temp.end() );
            }
            res.push_back(temp);
            tag*=( -1 );
        }

        return res;
    }

};