This code gives me an error and i really dont know why, please help :)

Question

The input is a 2d array and i want to see how many times each element appears, for storing the value and the number count i use a 2d array that acts like a list, v[i][0] being the value and v[i][1] being the count for that value

#include <iostream>
#include <fstream>
using namespace std;
ifstream in("k.in");
ofstream out("k.out");
int main()
{
int n,m,ii=1;
in>>n>>m;
int arr[n][m];

for(int i=0;i<n;i++)
for(int j=0;j<m;j++)
in>>arr[i][j];

int v[n*m][2];

for(int i=0;i<n*m;i++)
v[i][0]=0,v[i][1]=0;

v[0][0]=arr[0][0];

for(int i=0;i<n;i++)
for(int j=0;j<m;j++)
for(int l=0;l<ii;l++)
if(arr[i][j]==v[l][0])v[l][1]++;
else v[ii][0]=arr[i][j],v[ii][1]=1,ii++;

for(int i=0;i<ii;i++)
out<<v[i][0]<<' '<<v[i][1]<<endl;
return 0;
}

Answer 1

Are you trying to run it in SoloLearn Code Playground?
Because you are trying to handle files ( "k.in" and "k.out" ), and you cannot do that with the distant compiler of Sololearn ^^

Answer 2

Doesn't the two lines with ifstream and ofstream declaration need to be in the main() block?
( I have very few experience with c++, almost none with handling files ^^ )

Answer 3

I think I get it ^^

Nested loops for doing count is buggy: you iterate over length of the 'v' array to verify if the actual value is already registered, and add a new element to it if actual value is different of EACH values already registered... To fix it, do that:

int f;

for(int i=0;i<n;i++)
for(int j=0;j<m;j++)
{
f=-1;
for(int l=0;l<ii;l++)
if(arr[i][j]==v[l][0]) { f=l; break; }
if (f!=-1) v[f][1]++;
else v[ii][0]=arr[i][j],v[ii][1]=1,ii++;
}

For information, to debug it, I replaced all file in/out by console in/out, and add a lot ( progressivly ) of console output to log and verify that each arrays, variables, have expected values... So I noticed that 'v' array was too much growing, and 'ii' index overflow 'n*m', so all breaks without output ^^

Answer 4

I'm not trying in sololearn :/

Answer 5

the file declaration doesn't need to be inside the main