SOURCE

function isPail( head ) {
    let arr1=[],arr2=[]
    let cur=head
    while(cur){
        arr1.push(cur.val)
        arr2.push(cur.val)
        cur=cur.next
    }
    arr1.reverse()
    for(let i=0;i<arr1.length;i++){
        if(arr1[i]!=arr2[i]){
            return false
        }
    }
    return true
}
// module.exports = {
//     isPail : isPail
// };