http://oj.leetcode.com/problems/binary-tree-preorder-traversal/
二叉树的先跟遍历,写的是递归版本,也可以使用stack来进行,替代了递归函数。
class Solution { public: void preOrder(TreeNode *root,vector<int> &ans) { ans.push_back(root->val); if(root->left) preOrder(root->left,ans); if(root->right) preOrder(root->right,ans); } vector<int> preorderTraversal(TreeNode *root) { vector<int> ans; if(root) preOrder(root,ans); return ans; } };