Execution Timed Out (12000 ms): How can I optimize this code

Question

My task on codewars was to return true or false depending if the input number is narcissistic number (e.g. 153 = 1^3 + 5^3 + 3^3). But when I tested my code it said that Execution Timed Out (12000 ms) and that I should optimize the code further.

Does anyone know how can i optimize the code below? The code below is written in C#.

public class Kata
{
  public static bool Narcissistic(int value)
  {
    int digit = 0;
    int tempValue=value;
    int checkValue=value;
    int num;
    double sum = 0;

    //number of digits
    while(value!=0){
      value = value%10;
      digit++;
      value=value/10;
    }
    
    //sum
    while(tempValue!=0){
      num=tempValue%10;
      sum=sum+pow(num,digit);
      num=num/10;
    }
    if(sum==checkValue){
      return true;
    }else 
      return false;
  }
  
  //power
  private static int pow(int a,int b){
    int temp = a;
    for(int i=1;i<b;i++){
      a=a*temp;
    }
    return a;
  }
}

Answer 1

In your code tempValue was condition in loop but you never change the value so it's an infinity loop, not about performance

Maybe you can replace

while(tempValue!=0) {
    num=tempValue%10;
    sum=sum+pow(num,digit);
    num=num/10;
}

to

tempValue = -1;
while (tempValue != 0)
{
        int num = tempValue % 10;
        sum += Math.Pow(num, digit);
        tempValue /= 10;
}

Test case

Kata.Narcissistic(153);
// true

// DEBUG / NET6 [If you have care about performance]
// Time elapsed (ms): 6,998
// Time elapsed (ns): 7046900