C Exercises: Display and count the number of Lychrel numbers within a specific range.

C Numbers: Exercise-9 with Solution

Write a program in C to display and count the number of Lychrel numbers within a specific range (from 1 to a specific upper limit).

Test Data
Input the upper limit: 1000

Sample Solution:

C Code:

# include <stdio.h>
# include <stdbool.h>
# include <stdlib.h>

bool palindrome ( unsigned long long int i );
unsigned long long int reverse ( unsigned long long int i );
bool lychrel ( unsigned long long int i );

int main ( void )
{
	unsigned long long int i=0;
	int count=0,ulmt;
  printf("\n\n Display and count number of Lychrel numbers within a specific range: \n");
  printf(" -------------------------------------------------------------------------\n");
  printf(" Input the upper limit: ");
  scanf("%d",&ulmt);
  	printf("\n The Lychrel numbers are:  \n");
	for(i=1;i<ulmt;i++)
	{
		if(lychrel(i))
		{
		    printf(" %llu ",i);
			count++;
		}
	}
	printf("\n The number of  Lychrel numbers are:  %d\n\n",count);
	return 0;
}
bool lychrel ( unsigned long long int i )
{
	int j; /*iteration counter*/
	bool lychrel = true;
	i = i + reverse ( i );

	for ( j = 1; j <= 30 ; j++ )
	{
		if ( palindrome ( i ) )
		{
			lychrel = false;
			break;
		}
		i = i + reverse ( i );
	}

	return lychrel;
}
unsigned long long int reverse ( unsigned long long int i )
{
	unsigned long long int ret = 0;
	while ( i != 0 )
	{
		ret *= 10;
		ret += i % 10;
		i /= 10;
	}
	return ret;
}

bool palindrome ( unsigned long long int i )
{
	return ( i == reverse ( i ) );
} 

Sample Output:

 Input the upper limit: 1000                                                                                  
                                                                                                              
 The Lychrel numbers are:                                                                                     
 196  295  394  493  592  689  691  788  790  879  887  978  986                                              
 The number of  Lychrel numbers are:  13

Pictorial Presentation:

Flowchart:

C Programming Code Editor:

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