Thread: Errors in Palindrome Finder

Ok, so I tried the exercise over on https://www.spoj.pl/problems/PALIN/
The rules state:
"A positive integer is called a palindrome if its representation in the decimal system is the same when read from left to right and from right to left. For a given positive integer K of not more than 1000000 digits, write the value of the smallest palindrome larger than K to output. Numbers are always displayed without leading zeros."


I gave it my best shot, fellas, but it just won't compile. have a ........ing field day, I'm spent for today.

Code:

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

void input(int *numberPointerOne);
int test(int *numberPointerTwo);
int *reverse(int*orig, unsigned short int b);

int main (int argc, const char * argv[]) {
    int number[1000000];
	int returned = 0;
	int lengthTwo;
	input(number);
	
	while(returned = 0){
	returned = test(number);
	
	lengthTwo = strlen(number);
	reverse(number, lengthTwo);
	}
	
    printf("%d", returned);
    return 0;
}

void input(int *numberPointer){
	printf("enter positive integer:\t");
	scanf("%d", numberPointer);
	fpurge(stdin);
}

int test(int *numberPointerTwo){
	int lengthOne;
	int before, after;
	before = atoi(numberPointerTwo);
	lengthOne = strlen(numberPointerTwo);
	after = reverse(numberPointerTwo, lengthOne);
	
	if(before == after){
		return after;
	} else{
		return 0;
	}
}
	
int *reverse(int *orig, unsigned short int b){
	unsigned short int a=0;
	int swap;
	for(a;a<--b;a++){
	swap=orig[a];
	orig[a]=orig[b];
	orig[b]=swap;
	}
	return orig;
}

A million digits!?

Originally Posted by AntP

A million digits!?

Use a list.

Code:

	
int *reverse(int *orig, unsigned short int b){
	unsigned short int a=0;
	int swap;
	for(a;a<--b;a++){   <--- Error?
	swap=orig[a];
	orig[a]=orig[b];
	orig[b]=swap;
	}
	return orig;

Originally Posted by laserlight

Yes, but it is a logic error with an edge case, not a compile error.

Yeah, that's why the question mark... I don't have time to play with this today but I thought maybe that's where the problem was.