1 /** 2  * Definition of TreeNode: 3  * class TreeNode { 4  * public: 5  *     int val; 6  *     TreeNode *left, *right; 7  *     TreeNode(int val) { 8  *         this->val = val; 9  *         this->left = this->right = NULL;10  *     }11  * }12  */13 class Solution {14     /**15      * @param root: The root of binary tree.16      * @return: Postorder in vector which contains node values.17      */18 public:19     vector
     
       postorderTraversal(TreeNode *root) {20         // write your code here21         vector
      
        result;22         if (root == NULL) {23             return result;24         }25         if (root->left != NULL) {26             vector
       
         left = postorderTraversal(root->left);27             result.reserve(result.size() + left.size());28             result.insert(result.end(), left.begin(), left.end());29         }30         if (root->right != NULL) {31             vector
        
          right = postorderTraversal(root->right);32             result.reserve(result.size() + right.size());33             result.insert(result.end(), right.begin(), right.end());34         }35         result.push_back(root->val);36         return result;37     }38 };
        
       
      
     

1 /** 2  * Definition of TreeNode: 3  * class TreeNode { 4  * public: 5  *     int val; 6  *     TreeNode *left, *right; 7  *     TreeNode(int val) { 8  *         this->val = val; 9  *         this->left = this->right = NULL;10  *     }11  * }12  */13 class Solution {14     /**15      * @param root: The root of binary tree.16      * @return: Postorder in vector which contains node values.17      */18 public:19     vector
     
       postorderTraversal(TreeNode *root) {20         // write your code here21         vector
      
        result;22         if (root == NULL) {23             return result;24         } else {25             postorderCore(root, result);26         }27         return result;28     }29     void postorderCore(TreeNode *root, vector
       
         &result) {30         if (root == NULL) {31             return;32         }33         if (root->left != NULL) {34             postorderCore(root->left, result);35         }36         if (root->right != NULL) {37             postorderCore(root->right, result);38         }39         result.push_back(root->val);40         return;41     } 42 };
       
      
     

1 /** 2  * Definition of TreeNode: 3  * class TreeNode { 4  * public: 5  *     int val; 6  *     TreeNode *left, *right; 7  *     TreeNode(int val) { 8  *         this->val = val; 9  *         this->left = this->right = NULL;10  *     }11  * }12  */13 class Solution {14     /**15      * @param root: The root of binary tree.16      * @return: Postorder in vector which contains node values.17      */18 public:19     vector
     
       postorderTraversal(TreeNode *root) {20         // write your code here21         vector
      
        result;22         if (root == NULL) {23             return result;24         }25         26         TreeNode *cur = root, *pre = NULL;27         stack
       
         sta;28         29         while (cur != NULL || !sta.empty()) {30             while (cur != NULL) {31                 sta.push(cur);32                 cur = cur->left;33             }34             cur = sta.top();35             if (cur->right == NULL || cur->right == pre) {36                 sta.pop();37                 result.push_back(cur->val);38                 pre = cur;39                 cur = NULL;40             } else {41                 cur = cur->right;42             }43         }44         return result;45     }46 };