Minimum Depth Of Tree

MinimumDepthTree01.java

 public int minDepth(TreeNode A) {
        
        if(A== null){
            return 0;
        }
        
        if(A.left == null && A.right == null){
            return 1;
        }
        
        if(A.left == null){
            return minDepth(A.right)+1;
        }
        
        if(A.right == null){
            return minDepth(A.left)+1;
        }
        
        return Math.min(minDepth(A.right),minDepth(A.left))+1;
        
    }

MinimumDepthTree02.java

public int minimumDepth(TreeNode root){
   return  utility(root,0);
}

private int utility(TreeNode n, int level){
  
  if(n == null) return level;
  level++;
  return Math.min(utility(n.left,level),utility(n.right,level);
}