codeforces runtime error on pset 1A - c

Question

I am trying to solve problem 1A on codeforces
but i keep getting Test: #1, time: 0 ms., memory: 1828 KB, exit code: 1, checker exit code: 0, verdict: RUNTIME_ERROR
you can check my entry here and find my code below , i tried to to run the program locally and it works fine and it passed the test case on the website
#include<stdio.h>
int calculateSquare(int n , int m , int a){
int length=0;
int width = 0;
if(n%a != 0){
length = (n/a)+1 ;
}
else{
length = n/a ;
}
if(m%a != 0){
width = (m/a)+1 ;
}
else{
width = m/a ;
}
return length*width ;
}
void main(){
int n,m,a ;
scanf("%d %d %d",&n,&m,&a);
int output = calculateSquare(n,m,a);
printf("%d",output);
}

Answer 1

int calculateSquare(int n , int m , int a)
return type is int and return value is length*width
In the worst case a would be 1 and n, m would be 109 as stated in the problem
Input
The input contains three positive integer numbers in the first
line: n,  m and a (1 ≤  n, m, a ≤ 109).
So the return type int cannot hold the returned value for such case.
Better using long long int if the compilation is conform with C99 standard.

Answer 2

I modified your code as given below which seems to be working fine :
#include <stdio.h>
long long int calculateSquare(long n , long m , long a){
long length=0;
long width = 0;
if(n%a != 0){
length = (n/a)+1 ;
}
else{
length = n/a ;
}
if(m%a != 0){
width = (m/a)+1 ;
}
else{
width = m/a ;
}
long long store = length*widthl
return store;
}
int main(){
long int n,m,a ;
scanf("%ld %ld %ld", &n, &m, &a);
long int output = calculateSquare(n,m,a);
printf("%ld\n", output);
return 0;
}

Answer 3

when trying to 'beat the clock', it is best to not use 'expensive' I.O functions.
Suggest the following two functions:
#include <stdio.h>
void fastRead( size_t *a );
void fastWrite( size_t a );
inline void fastRead(size_t *a)
{
int c=0;
// note: 32 is space character
while (c<33) c=getchar_unlocked();
// initialize result value
*a=0;
// punctuation parens, etc are show stoppers
while (c>47 && c<58)
{
*a = (*a)*10 + (size_t)(c-48);
c=getchar_unlocked();
}
//printf( "%s, value: %lu\n", __func__, *a );
} // end function: fastRead
inline void fastWrite(size_t a)
{
char snum[20];
//printf( "%s, %lu\n", __func__, a );
int i=0;
do
{
// 48 is numeric character 0
snum[i++] = (char)((a%10)+(size_t)48);
a=a/10;
}while(a>0);
i=i-1; // correction for overincrement from prior 'while' loop
while(i>=0)
{
putchar_unlocked(snum[i--]);
}
putchar_unlocked('\n');
} // end function: fastWrite

Answer 4

This occurs when an uninitialized variable is passed as an Array or Vector size.
Code with error:
int m;
vector<int> arr(m);
//throws Exit code 2147483647
//default value of uninitialized int variable is 4201296 > 10^5
//so the vector<int> can't be created.
Correct answer:
int m;
cin>>m; //this works
vector<int> arr(m);