Algorithm for PRIMES working on ideone but not accepted here!

Sorry, for asking this question but I tried to mean 1 million not billion and I am a beginner so I can’t understand what’s causing the problem in this program because this works fine for inputs smaller than 1 million but anything larger than that causes some weird problems.
By the way thanks for your time.

Well I think I figured the mistake out but now this time the Judge says time limit exceeded and may be memory limit too. Now what to do next this is the best algorithm that I can understand…
here’s the code

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

int main(){
	int t;
	scanf("%i", &t);
	if(t > 10)
		exit(1);

	unsigned long m[t], n[t];
	for(int i=0; i<t; i++){
		scanf("%li %li", &m[i], &n[i]);
	}


	for(int i=0; i<t; i++){
		if(m[i] < 1 || n[i] > 1000000000)
			continue;
		if((n[i]-m[i]) > 100000)
			continue;
		
		unsigned short prime[n[i]+1];
		
		if(m[i] < 2) m[i] = 2;

		for(long j=0; j<=n[i]; j++){
			prime[j] = 1;
		}

		for(long p=2; p*p<=n[i]; p++){
			if(prime[p] == 1){
				for(long q=p*p; q<=n[i]; q+=p)
					prime[q] = 0;
			}
		}

		for(long j=m[i]; j<=n[i]; j++){
			if(prime[j] == 1)
				printf("%li\n", j);
		}

		printf("\n");
	}

	return 0;
}

Well I have found a better algorithm i.e. segmented sieve that reduces the memory (shows 4.7M down from 2048M) usage significantly but still somehow the judge says that It gives wrong answers.
why is this giving me wrong answer?

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

void simpleSieve(int start, int limit, int* prime, int* pointer){
	int marks[limit + 1];
	for(int i=0; i<limit; i++)
		marks[i] = 1;

	for(int p=2; p*p<limit; p++){
		if(marks[p]){
			for(int i=p*p; i<limit; i+=p)
				marks[i] = 0;
		}
	}

	for(int i=2; i<limit; i++){
		if(marks[i]){
			prime[*pointer] = i;
			*pointer = *pointer + 1;
			if(i>=start)
				printf("%i\n", i);
		}
	}

}

void segmentedSieve(int m, int n){
	int limit = floor(sqrt(n)) + 1;
	int prime[(int)floor((int)(limit/2))];
	int pointer = 0;
	simpleSieve(m, limit, prime, &pointer);

	int low = (m>limit)?m:limit;
	int high = low + limit;

	while(low < n){
		if(high >= n)
			high = n;

		int mark[limit + 1];
		for(int i=0; i<=limit; i++)
			mark[i] = 1;

		for(int i=0; i<pointer; i++){
			int loLim = floor((int)(low/prime[i])) * prime[i];
			if(loLim < low)
				loLim += prime[i];

			for(int j=loLim; j<=high; j+=prime[i])
				mark[j-low] = 0;
		}

		for(int i=low; i<=high; i++){
			if(mark[i-low])
				printf("%i\n", i);
		}

		low +=limit;
		high += limit;
	}
}

int main(){
	int t;
	scanf("%i", &t);
	int m[t], n[t];

	for(int i=0; i<t; i++)
		scanf("%i %i", &m[i], &n[i]);

	for(int i=0; i<t; i++){
		if(m[i] < 1 || n[i] > 1000000000)
			continue;
		if(n[i]-m[i] >= 100000)
			continue;
		segmentedSieve(m[i], n[i]);
		printf("\n");
	}

	return 0;
}

Should I exit if one of edge case is met like (m-n) is greater than 1k?
And thanks for your precious time…

Well Thank You for your time and support…
The bug turn out to be an equals sign that should not belong there…🤦
Finally…

Sir It would be really helpful if You can tell me what’s wrong on another problem that Also gives wrong answer but I can’t find which input is causing the issue…
The problem is based on Palindrome:

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

int isPalin(long number){
	long a = number;
	long b = 0;
	while(a>0){
		b = b * 10 + a % 10;
		a /= 10;
	}
	if(b == number)
		return 1;
	return 0;
}

int main(){
	int t;
	scanf("%i", &t);
	long k[t];

	for(int i=0; i<t; i++){
		char s[10];
		scanf("%s", s);
		k[i] = atoi(s);
	}

	for(int i=0; i<t; i++){
		if(k[i] > 1000000)
			continue;
		long a = k[i] + 1;
		while(!isPalin(a))
			a++;
		printf("%i\n", a);
	}

	return 0;
}

Thank You once more for supporting…

Now I’ve got the problem and solved it but The Judge says SIGABRT for some reason.
I guess it’s using a lot of memory but when I tested it in ideone it is showing memory usage in KBs.
So i couldn’t get any idea about the bug…
Here’s the code:

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

char *strrev(char *str){
	char *p1, *p2;
	if(!str || !*str)
		return str;
	for( p1 = str, p2 = strlen(str)+str-1; p1<p2; ++p1, --p2){
		*p1 ^= *p2;
		*p2 ^= *p1;
		*p1 ^= *p2;
	}
	return str;
}

void append(char *s, char c){
	int len = strlen(s);
	s[len] = c;
	s[len + 1] = '\0';
}

char *removeLeadingZeros(char *s){
	char *tmp;
	for(int i=0; i<strlen(s); i++){
		if(s[i] != '0'){
			tmp = s+i;
			break;
		}
	}
	return tmp;
}

void palin(char *s){
	//printf("s: %s\n", s);
	int midpoint = floor(strlen(s)/2);
	char p[midpoint];
	char q[midpoint];
	int odd = strlen(s) % 2;
	strncpy(p, s, midpoint);
	p[midpoint] = '\0';
	strcpy(q, s+midpoint+odd);
	//printf("p: %s\tq: %s\n", p, q);
	int i=midpoint-1, j=0;
	do{
		int a, b;
		a = p[i];
		b = q[j];
		if(a == b){
			i--;
			j++;
			continue;
		}
		if(a < b){
			if(odd)
				s[midpoint] += 1;
			else
				p[midpoint-1] += 1;
		}
		break;
	}while(1);
	char rev[strlen(p)];
	strcpy(rev, p);
	strrev(rev);
	//printf("p: %s\nrev: %s\n", p, rev);
	if(odd)
		append(p, s[midpoint]);
	//printf("p: %s\tq: %s\n", p, q);
	strcat(p, rev);
	printf("%s\n", p);
}

int main(){
	int t;
	scanf("%i", &t);
	while(t--){
		char s[1000000];
		scanf("%s", s);
		char *p;
		p = removeLeadingZeros(s);
		s[strlen(s) - 1] += 1;
		palin(p);
	}
	return 0;
}

And let me know if I create a separate thread for this problem.

I have created a separated thread for this problem.
Please check it out and see if you can help with that…
here’s the link