How do i design an Algorithm to check if a number is an Armstrong number?

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Check Armstrong Number
1.start
2. input n.
3. n1:=n.
4. let s := 0.
5. r := n1%10.
6. s:=s+ r*r*r.
7. n1 :=n1/10.
8. if n1<>0 then goto step 5.
9.  if n=s then
10. print "ARMSTRONG NO"
11. else
12.print "NOT ARMSTRONG NO"
13. end

The above algorithm would check only the 3 digit numbers, if u need it for all digit numbers then u need to request me again. CHAO.

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saurabh

  • Sep 16th, 2006
 

could you please send armstrong algo for the all digits

thnking you

saurabh

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jyoti

  • Sep 27th, 2006
 

simply add a do-while loop to it for (n>0) and it whould wor for all number of digits
 
jyoti
www.jyoticlub.jaijyoti.com

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JonBruse

  • Nov 14th, 2006
 

in C#:

public static bool isArmstrong(int intInteger)

{

// Declarations

int Length, Total1, Temp;

string strString = intInteger.ToString();

Total1 = 0;

//get length of number

Length = strString.Length;

//iterate through each digit, get n power, add to sum

for (int i = 0; i <= Length - 1; i++)

{

Temp = Convert.ToInt32(strString.Substring(i, 1).ToString());

Total1 += Convert.ToInt32(System.Math.Pow(Convert.ToDouble(Temp), Convert.ToDouble(Length)));

}

if (Total1 == intInteger)

{

return true;

}

else

{

return false;

}

}

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First of all I would like to introduce to you with amstrong number.

Lets take an example: 153 which is amstrong number because 153 = (1*1*1) + (5*5*5) + (3*3*3) i.e.
153 = 1^3 + 5^3 + 3^3(where ^ indicates power i.e. 3^3 is 3*3*3)

Now logic behind writing the program to check the amstrong number:

1: initialize the number i.e. num
y <-- num, sum <-- 0, temp <-- 0
2: repeat step untill y !=0
i: calculate y%10 and store it in temp
ii: calculate temp*temp*temp and add it with the previous value of sum
iii: find y <-- y/10
3: check whether sum is equal to num , if so num is amstrong number
4: otherwise num is not an amstrong number

Here is the actual program which implements the above logic and find out whether a number is amstrong number or not:

<-------------------------------------------------------------------------------------------->
#include
<stdio.h>
void main()
{
int num=153;
int y=num,sum=0,temp;
while(y != 0)
{
temp = y%10;
sum = sum+temp*temp*temp;
y = y/10;
}
if(sum == num)
printf("amstrong number");
else
printf("Not amstrong number");
}
<------------------------------------------------------------------------------------>

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Kapil S Shinde

  • Feb 25th, 2014
 

Code
  1. start

  2. Accept num

  3.  

  4. noOfDigit=calculate number of digits   //use counting digit function

  5.  

  6. while(num!=0)

  7. {

  8. remainder=inum%10;

  9. sum=sum+pow(remainder,noOfDigit);     //use power function from math.h header file

  10. num=num/10;

  11. }

  12. if(sum==num)

  13.  return true

  14. else

  15.  return false

  16. stop

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jbode

  • Mar 7th, 2014
 

First, count up the number of digits in the candidate value; an easy way to do this is take the floor value of the log of the number and add 1 (for example, floor(log10(1234)) = 3, so 3 + 1 = 4 digits).
Then extract each digit (an easy way to do this is to use a remainder or modulus operation), raise it to the power of the number of digits, and sum the results together.
Compare this sum to your candidate value; if they're equal, then the candidate value is narcissistic. Attached is an example written in C that examines a single number or range of numbers using base 10, along with some sample output.

Code
  1. /**

  2.  * This program analyzes a range of numbers to see if they are

  3.  * narcissistic or Armstrong numbers (sum of its own digits, each

  4.  * raised to the power of the number of digits) in base 10.

  5.  *

  6.  * The output is simply the number if it meets the necessary

  7.  * criteria.

  8.  */

  9. #include <stdio.h>

  10. #include <stdlib.h>

  11. #include <ctype.h>

  12. #include <math.h>

  13.  

  14. /**

  15.  * Test a candidate value to see if it is narcissisitc.

  16.  * Returns true (1) or false (0).

  17.  */

  18. int test( long cand )

  19. {

  20.   int digits = (int) log10( (double) cand ) + 1;

  21.   long sum = 0;

  22.   long temp = cand;

  23.  

  24.   for ( int i = 0; i < digits; i++ )

  25.   {

  26.     int curdigit = temp % 10;

  27.     temp /= 10;

  28.     sum += (long) pow( (double) curdigit, digits );

  29.   }

  30.  

  31.   return sum == cand;

  32. }

  33.  

  34. /**

  35.  * Process the command line arguments; must provide

  36.  * a valid integer or range of integers.

  37.  */

  38. int getargs( int argc, char **argv, long *start, long *end )

  39. {

  40.   int result = 1;

  41.   if ( argc < 2 )

  42.   {

  43.     result = 0;

  44.   }

  45.   else if ( argc >= 2 )

  46.   {

  47.     char *chk;

  48.     long val = strtol( argv[1], &chk, 0 );

  49.     if ( isspace( *chk ) || *chk == 0 )

  50.       *start = *end = val;

  51.     else

  52.       result = 0;

  53.  

  54.     if ( argc > 2 )

  55.     {

  56.       val = (int) strtol( argv[2], &chk, 0 );

  57.       if ( isspace( *chk ) || *chk == 0 )

  58.         *end = val;

  59.       else

  60.         result = 0;

  61.     }

  62.   }

  63.  return result;

  64. }

  65.  

  66. /**

  67.  * Main program; loop through the specified range

  68.  * of values and test each for narcissism; if

  69.  * the number is narcissistic, write it to

  70.  * standard output.

  71.  */

  72. int main( int argc, char **argv )

  73. {

  74.   long start=0, end=0;

  75.   const char *usage = "USAGE: %s start [end]n";

  76.   if ( !getargs (argc, argv, &start, &end ))

  77.   {

  78.     fprintf( stderr, usage, argv[0] );

  79.     return EXIT_FAILURE;

  80.   }

  81.  

  82.   for( long t = start; t <= end; t++ )

  83.     if ( test( t ))

  84.       fprintf( stdout, "%ld

  85. ", t );

  86.  

  87.   return EXIT_SUCCESS;

  88. }

  89.  

  90. [fbgo448@n9dvap997]~/prototypes/armstrong: gcc -o armstrong -std=c99 -pedantic -g -Wall -Werror armstrong.c -lm

  91. [fbgo448@n9dvap997]~/prototypes/armstrong: ./armstrong 153

  92. 153

  93. [fbgo448@n9dvap997]~/prototypes/armstrong: ./armstrong 154

  94. [fbgo448@n9dvap997]~/prototypes/armstrong: ./armstrong 0 10000

  95. 0

  96. 1

  97. 2

  98. 3

  99. 4

  100. 5

  101. 6

  102. 7

  103. 8

  104. 9

  105. 153

  106. 370

  107. 371

  108. 407

  109. 1634

  110. 8208

  111. 9474

  112.  

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