No response from recursive function

Question

I want to create a function that is able to determine if a number is same or palindrome. if a given number is palindrome or same then return 2 otherwise if it is not palindrome or same then i need check it twice by increment the given number by 1. after that if it palindrome or same then return 1. if no palindrome or same number found then return 0. i write the function which is giving me the exact result when i give the number as 11211 but the function don't show any response if i enter 1122 or other random value. please help me to find where the error of my function.

function sameOrPalindrome(num) {
  var c = 0;
  var al = 0;
  var normalArray = num.toString().split("");
  var revArray = num.toString().split("").reverse();
  for (var i = 0; i < normalArray.length; i++) {
    if (normalArray[i] != revArray[i]) {
      c++;
    }
  }
  if (c == 0) {
    return 2;
  } else {
    num++;
    al = sameOrPalindrome(num);
    if (al == 2) {
      return 1;
    } else {
      num++;
      al = sameOrPalindrome(num);
      if (al == 2) {
        return 1;
      }
    }
  }
  return 0;
}

console.log("1233",sameOrPalindrome(1233))

Answer 1

here is my solution to this problem:

function reversedNum(num) {
    return (
    parseFloat(
      num
        .toString()
        .split('')
        .reverse()
        .join('')
      ) * Math.sign(num)
      )                 
     }
    


      function sameOrPalindrome(num) {
        if (num === reversedNum(num)) {
          return 2;
        } else {
          num++;
          if (num === reversedNum(num)) {
            return 1;
          } else {
            num++;
            if (num === reversedNum(num)) {
              return 1;
            }
          }
        }
        return 0;
      }

      console.log("1233",sameOrPalindrome(1233))

Answer 2

We should always strive to make function more effiecient... you dont need to run full loop. plus actual checking of palindrome can me modularized




    function isSameOrPalindrome(num) {
      var normalArray = num.toString().split("");
      var revArray = num.toString().split("").reverse(),
      i;
      for (i = 0; i < normalArray.length / 2; i++) {
        if (normalArray[i] !== revArray[i]) {
         break;
        }
      }
      if (i >= normalArray.length/2) {
        return "Palindrome";
      } else {
        return "Not Palindrome";
      }
    }
function doCheck(num) {
	var isPalindrome = isSameOrPalindrome(num);
  		console.log(isPalindrome);
  		if(isPalindrome === "Palindrome") {
      	return 2;
      } else {
      	num++;
        isPalindrome = isSameOrPalindrome(num);
        if(isPalindrome === "Palindrome") {
      	return 1;
      } else {
      	return 0
      }
      }
}
    console.log("100",doCheck(100));

Answer 3

function check_palindrom(num){
    var c1 = 0;
    var normalArray = num.toString().split("");
    var revArray = num.toString().split("").reverse();
    for (var i = 0; i < normalArray.length; i++) {
        if (normalArray[i] == revArray[i]) {
            c1++;
        }
    }
    if(c1==0){
      return 2;
    }else{
      return 1;
    }
}//check_palindrom

function my_fun_check_palindrome(mynum){
    //console.log(mynum);
    var num = mynum;
    var c2 = 0;
    var al = 0;
    var normalArray = mynum.toString().split("");
    var revArray = mynum.toString().split("").reverse();
    for (var j = 0; j < normalArray.length; j++) {
        if (normalArray[j] == revArray[j]) {
            c2++;
        }
    }
    if(c2==0){
      console.log('Number is palindrome. Return Value :'+ 2);
    }
    if(1){
      console.log('checking again with incremeting value my one');
      num = parseInt(num)+1;
      al = check_palindrom(num);
      if(al==2){
        console.log('Number is palindrome. Return Value :'+ 1);
      }else{
        console.log('Number is not palindrome. Return Value :'+ 0);
      }
    }
    
    
}//my_fun_check_palindrome

console.log(my_fun_check_palindrome(1122));
console.log(my_fun_check_palindrome(11221));

Answer 4

Your function needs to know if it should not call itself any more, e.g. when it's doing the second and third checks:

function sameOrPalindrome(num,stop) {      // <-- added "stop"
  var c = 0;
  var al = 0;
  var normalArray = num.toString().split("");
  var revArray = num.toString().split("").reverse();
  for (var i = 0; i < normalArray.length; i++) {
    if (normalArray[i] != revArray[i]) {
      c++;
    }
  }
  if (c == 0) {
    return 2;
  } else if(!stop) {                       // <-- check of "stop"
    num++;
    al = sameOrPalindrome(num,true);       // <-- passing true here
    if (al == 2) {
      return 1;
    } else {
      num++;
      al = sameOrPalindrome(num,true);     // <-- and also here
      if (al == 2) {
        return 1;
      }
    }
  }
  return 0;
}

for(let i=8225;i<8230;i++)
  console.log(i,sameOrPalindrome(i));

Answer 5

Question: I assumed if palindrome test is true at first time then return 2. if not try incrementing by one and test the palindrome again . if true return 1 else try incrementing for last time and check the palindrome if true return 1 else 0.

Store string into array first and do arr.reverse().join("") to compare

  let arr=num.toString().split("");
  if(num.toString() == arr.reverse().join(""))

function sameOrPalindrome(num, times) {
  let arr = num.toString().split("");
  if (num.toString() == arr.reverse().join("")) {
    if (times == 3) return 2
    else return 1;
  } else if (times > 0) {
    num++; times--;
    return sameOrPalindrome(num, times);
  } else return 0
}
console.log(sameOrPalindrome(123321, 3));
console.log(sameOrPalindrome(223321, 3));
console.log(sameOrPalindrome(323321, 3));

Answer 6

Perhaps not using recurse - I think your function loops

const allEqual = arr => arr.every( v => v === arr[0] )
const sameOrPalin = num => {
  const str = String(num);
  let arr = str.split("")
  if (allEqual(arr)) return 2
  arr.reverse();
  if (arr.join("") === str) return 1;
  return 0
};
console.log("1111",sameOrPalin(1111));
console.log("2111",sameOrPalin(2111));
console.log("2112",sameOrPalin(2112));
console.log("1234",sameOrPalin(1234));

for (let i = 2111; i<=2113; i++) console.log(i,sameOrPalin(i));