Sum of Left Leaves @LeetCode

PROBLEM :

Find the sum of all left leaves in a given binary tree.

Example:

    3
   / \
  9  20
    /  \
   15   7

There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24.

--------------------------------------------------------------------------------
SIMPLE c++ IMPLEMENTATION :( Recursive Solution )
--------------------------------------------------------------------------------

 /**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */

class Solution {
public:
    int sumOfLeftLeaves(TreeNode* root) {
        if(root==NULL)
            return 0 ;
        int l=0,r=0 ;
        if(root->right)
            r=sumOfLeftLeaves(root->right) ;
        if(root->left&&(root->left->left==NULL&&root->left->right==NULL))
            return root->left->val + r ;
        if(root->left)
            l=sumOfLeftLeaves(root->left) ;
     
        return l+r ;
    }
};

--------------------------------------------------------------------------------
SIMPLE c++ IMPLEMENTATION :( Iterative Solution )
--------------------------------------------------------------------------------

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */

class Solution {
public:
    int sumOfLeftLeaves(TreeNode* root) {
        if(root==NULL)
            return 0 ;
         
        queue<TreeNode*> que ;
        que.push(root) ;
        int sum=0 ;
     
        while(!que.empty()){
            int n=que.size() ;
            while(n--){
                TreeNode* node=que.front() ;
                que.pop() ;
             
                if(node->left!=NULL&&(node->left->left==NULL&&node->left->right==NULL))
                    sum+=node->left->val ;
                else if(node->left)
                    que.push(node->left) ;
                 
                if(node->right!=NULL)
                    que.push(node->right) ;
            }
        }
        return sum ;
    }
};

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