check if an integer exists in a specific column of an array

Question

I 've to do the following exercise:

Write a function that given two integers (x and k ) and a M X N matrix, returns TRUE if there is an element that occurs at least k times in at least x columns of the matrix.

this is my solution but there is something wrong:

#include <iostream>
using namespace std;

const int DIM = 3;

bool check ( int matrix[DIM][DIM], int element,  int k,  int x )
{
    bool occur = false;
    int i,j = 0;
    for ( i=0; i<DIM; i++ )
    {
        for ( j=0; j<DIM; j++)
        {
            while ( i<k && occur)
            {
                matrix[i][j] == element;
                i++;
            }
        }
    }
    return occur;
}

int main ()
{
    int matrix[DIM][DIM] = {{1,2,3},
                            {4,1,6},
                            {7,8,9}};
    int x = 2;
    int k = 1;
    int elemento = 1;
    if ( check (matrix, element, k , x))
    {
        cout << "l'elemento "<< elemento <<" ricorre "<< k <<" volta/e in "<< x <<" colonna/e";
    }
    return 0;
}

You never set occur. You need to sit and think about your algorithm. — mert
– mert, Commented Apr 22, 2012 at 13:33
For an error description like "something is wrong", our solution can't be much more than "fix something" :-) If you want more, first of all give all relevant information to describe your problem as precisely as you can. — Péter Török
– Péter Török, Commented Apr 22, 2012 at 13:35
i < k and matrix[i][j] == element; seems incorrect. Also what mert said. — Vinayak Garg
– Vinayak Garg, Commented Apr 22, 2012 at 13:49

Karolis Juodelė · Accepted Answer · 2012-04-22 13:35:03Z

1

You need to separate the task into smaller chunks. To check if a number occurs k times in x columns, first write a function to check if a number occurs k times in one column. That function will have a single for loop. When you write it, test it to see if you did it correctly. Then put that function in another, very similar for loop and you're done.

answered Apr 22, 2012 at 13:35

Karolis Juodelė

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Corwin · Accepted Answer · 2012-04-22 18:47:13Z

0

bool check(int matrix[M][N], int element, int k, int x)
{
        int c1 = 0;
        for (int i = 0; i < M; ++i) {
                int c2 = 0;
                for (int j = 0; j < N; ++j) {
                        if (matrix[i][j] == element)
                                ++c2;
                }
                if (c2 >= k)
                        ++c1;
        }
        return c1 >= x;
}

Optimize it yourself ;)

answered Apr 22, 2012 at 18:47

Corwin

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