BM31 对称的二叉树

/* function TreeNode(x) {
    this.val = x;
    this.left = null;
    this.right = null;
} */
function isSymmetrical(pRoot)
{
    // write code here
    function compareNodes(left,right){
        if(left === null && right!== null){
            return false
        }else if(right === null && left !== null){
            return false
        }else if(left === null && right === null){
            return true
        }else if(left.val !== right.val){
            return false
        }
        
        let outside = compareNodes(left.left,right.right)
        let inside = compareNodes(left.right,right.left)
        return outside&&inside
    }
    
    if(pRoot === null){
        return true
    }
    return compareNodes(pRoot.left,pRoot.right)
}
module.exports = {
    isSymmetrical : isSymmetrical
};