100. Same Tree leetcode

isSameTree.ts

// /
//  Definition for a binary tree node.
 class TreeNode {
     val: number
     left: TreeNode | null
     right: TreeNode | null
     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
         this.val = (val===undefined ? 0 : val)
         this.left = (left===undefined ? null : left)
         this.right = (right===undefined ? null : right)
     }
 }
 

function isSameTree(p: TreeNode | null, q: TreeNode | null): boolean {
    if(!p &&!q) return true
    else if(!p||!q) return false
    else if(p.val !==q.val)  return false
    else {
    return isSameTree(p.left,q.left)&&isSameTree(p.right,q.right)
    }
    

};