Cacher is the code snippet organizer for pro developers

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    
      
 public int sumOfLeftLeaves(TreeNode root) {
     if(root == null || root.left == null && root.right == null) return 0;
        
        int res = 0;
        Queue<TreeNode> queue = new LinkedList<>();
        queue.offer(root);
        
        while(!queue.isEmpty()) {
            TreeNode curr = queue.poll();

            if(curr.left != null && curr.left.left == null && curr.left.right == null) res += curr.left.val;
            if(curr.left != null) queue.offer(curr.left);
            if(curr.right != null) queue.offer(curr.right);
        }
        return res;
   }
    
}