// invert binary tree : (right node >> left node && left node >> right node )
const invertTree =(root)=>{
if(root===null) return root;
let queue =[root] ;
while(queue.length>0){
let node =queue.shift() ;
if(node !=null){
let hold = node.left ;
node.left =node.right;
node.right =hold ;
if(node.left) queue.push(node.left) ;
if(node.right) queue.push(node.right) ;
}
}
return root;
}