500 Factorial Problem - solve by Ariful Islam Shanto

///BISMILLAHIR-RAHMANIR-RAHIM

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

#define max 3000
#define tot 1001

char facto[1001][max + 1];
char serial_str[tot][5];
char one[] = "0001";

void create_serial_string(int x)
{
    int i, j;
    int sum = 0, carry = 0, temp;
    for(i = 3; i >= 0; i--){
        temp = serial_str[x - 1][i] + one[i] - '0' - '0' + carry;
        sum = temp % 10;
        carry = temp / 10;
        serial_str[x][i] = sum + '0';
    }
    serial_str[x][4] = '\0';
}

void serial_maker()
{
    int i, j;
    for(i = 0; i < tot; i++){
        for(j = 0; j < 4; j++){
            serial_str[i][j] = '0';
        }
    }
    for(i = 1; i < tot; i++){
        create_serial_string(i);
    }
}


void build_zero_string()
{
    int i, j;
    for(i = 0; i <= 1000; i++){
        for(j = 0; j < max; j++){
            facto[i][j] = '0';
        }
    }
}

void multiply_and_create_new_facto(int k)
{
    int product, carry = 0, character;
    int i, j, l = 0;
    for(j = 3, l = 1; j >= 0; j--, l++){
        carry = 0;
        for(i = max - 1; i >= 3; i--){
            product = (int)(facto[k - 1][i] - '0') * (int)(serial_str[k][j] - '0') + carry + facto[k][i - l + 1] - '0';
            carry = product / 10;
            character = (product % 10) + '0';
            facto[k][i - l + 1] = character;
        }
    }
    facto[k][max] = '\0';
}

void instruct_to_create_fibo()
{
    facto[0][max - 1] = '1', facto[0][max] = '\0';
    facto[1][max - 1] = '1', facto[1][max] = '\0';
    for(int i = 2; i <= 1000; i++){
        multiply_and_create_new_facto(i);
    }
}

int main()
{
    serial_maker();
    build_zero_string();
    instruct_to_create_fibo();

    int n, i, j;

    while(scanf("%d", &n) == 1){
        printf("%d!\n", n);
        for(i = 0; i < max; i++){
            if(facto[n][i] != '0'){
                for(j = i; j < max; j++){
                    printf("%c", facto[n][j]);
                }
                printf("\n");
                break;
            }
        }
    }

    return 0;
}

///ALHAMDULILLAH