Minimum Depth of a Binary Tree

Java Implementation of finding minimum depth of a binary tree iteratively.

import java.util.LinkedList;
import java.util.Queue;

class Solution
{
    static class TreeNode{
        int data;
        TreeNode left,right;
        TreeNode(int data)
        {
            this.data=data;
        }
    }
    static int minimumDepth(TreeNode root)
    {
      Queue<TreeNode> queue=new LinkedList();
      queue.add(root);
      int depth=0;
      while(!queue.isEmpty())
      {   
          int s=queue.size();
          depth++;
          for(int i=0;i<s;i++)
          {     
            TreeNode temp=queue.poll();
              
              if(temp.left==null && temp.right==null)
              return depth;
              
              if(temp.left!=null)
              queue.add(temp.left);
              if(temp.right!=null)
              queue.add(temp.right);
          }    
      }
      return depth;
    }
     public static void main(String[] args)
    {
        TreeNode root=new TreeNode(1);
        root.left=new TreeNode(2);
        root.right=new TreeNode(3);
        root.left.left=new TreeNode(4);
        root.left.right=new TreeNode(7);
        
        int depth=minimumDepth(root);
        System.out.println(depth);
        
    }
    }

Output: 2

Time Complexity- O(n)

Space Complexity- O(n)

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