# Share my Recursive and Iterative (using stack & queue) C++ Solution

• ``````//Solution 1 -- 6 ms 5.52%
/**
* 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) return 0;
int sum = 0;
sumOfLeftLeaves(root, false, sum);
return sum;
}
void sumOfLeftLeaves(TreeNode* root, bool ifLeft, int& sum){
if(!root) return;
if(!root->left && !root->right && ifLeft)
sum += root->val;
sumOfLeftLeaves(root->left, true, sum);
sumOfLeftLeaves(root->right, false, sum);
}
};

//Solution 2 -- 6 ms 5.52%
class Solution {
public:
int sumOfLeftLeaves(TreeNode* root) {
if(!root) return 0;
if(root->left && !root->left->right && !root->left->left)
return root->left->val + sumOfLeftLeaves(root->right);
return sumOfLeftLeaves(root->left) + sumOfLeftLeaves(root->right);
}
};

//Solution 3 -- 6 ms 5.52%
class Solution {
public:
int sumOfLeftLeaves(TreeNode* root) {
if(!root) return 0;
int sum = 0;
stack<TreeNode*> stk;
stk.push(root);
while(!stk.empty()){
TreeNode* cur =stk.top();
stk.pop();
if(cur->left && !cur->left->left && !cur->left->right)
sum += cur->left->val;
if(cur->right) stk.push(cur->right);
if(cur->left) stk.push(cur->left);
}
return sum;
}
};

//Solution 4 -- 6 ms 5.52%
class Solution {
public:
int sumOfLeftLeaves(TreeNode* root) {
if(!root) return 0;
int sum = 0;
queue<TreeNode*> q;
q.push(root);
while(!q.empty()){
TreeNode* cur =q.front();
q.pop();
if(cur->left && !cur->left->left && !cur->left->right)
sum += cur->left->val;
if(cur->left) q.push(cur->left);
if(cur->right) q.push(cur->right);
}
return sum;
}
};``````

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