Sorting matrix by even numbers in rows - c

Question

Okay, so I'm just starting to use this site, and I know my title is a bit confusing, but I will try to explain it here as best as I can. So I have to take a matrix from the input, count even and odd numbers in each row, then write the matrix with rows that have more even numbers first. Example:
Input:
3 3 // Dimensions
1 2 3 // Elemets
4 5 6
7 8 9
Output:
1 2 3 // Original matrix
4 5 6
7 8 9
1 2 // Number of even and odd elements in each row
2 1
1 2
4 5 6 // Matrix sorted by even numbers in rows
1 2 3
7 8 9
I did everything except figuring out how to write out the final matrix. Any help?
#include<stdio.h>
#include<stdlib.h>
int main() {
int row, column, temp, count;
int even[100], odd[100];
for (int i = 0; i < 100; i++)
even[i] = odd[i] = 0;
scanf("%d %d", &row, &column);
count = row;
int* matrix = (int*)malloc(row * column * sizeof(int));
for (int i = 0; i < row; i++)
for (int j = 0; j < column; j++)
scanf("%d", &*(matrix + i * column + j));
for (int i = 0; i < row; i++) {
for (int j = 0; j < column; j++)
printf("%d ", *(matrix + i * column + j));
printf("\n");
}
for (int i = 0; i < row; i++) {
for (int j = 0; j < column; j++) {
temp = *(matrix + i * column + j);
if (temp % 2 == 0)
even[i]++;
else odd[i]++;
}
}
for (int i = 0; i < count; i++)
printf("%d %d\n", even[i], odd[I]);
return 0;
}
If there are some errors with variable names, I was translating most of them here directly, so maybe I missed some of them, sorry in advance.

Answer 1

You can create the swap function first, then compare the even value between the rows.
// Swap 2 elements
void swap_elt(int *a, int *b) {
int temp = *a;
*a = *b;
*b = temp;
}
// swap row m and row n
void swap(int *matrix, int m, int n, int column) {
for (int j = 0; j < column; ++j)
{
swap_elt(matrix + m * column + j, matrix + n * column + j);
}
return;
}
The for loop for compare the even value between the rows:
for (int i = 0; i < count; i++) {
for (int j = i; j < count; j++)
{
if (even[i] < even[j]) {
swap(matrix, i, j, column);
}
}
}
Test:
3 3
1 2 3
4 5 6
7 8 9
1 2 3
4 5 6
7 8 9
1 2
2 1
1 2
4 5 6
1 2 3
7 8 9

Answer 2

I won't say that this is 100% the answer but I tried my best (Sorry that my solution is a little different, I think I do understand your question but I can't make my answer better. Edit: I also include user3386109's idea too (at the bottom of my answer).
#include <stdio.h>
int main ()
{
int row, col;
scanf ("%d %d%*c", &row, &col);
int mtx[row][col];
for (int x=0; x<row; x++)
{
for (int y=0; y<col; y++) scanf ("%d%*c", &mtx[x][y]);
}
//Printing the original matrix
for (int x=0; x<row; x++)
{
for (int y=0; y<col; y++)
{
if (y) printf (" %d", mtx[x][y]);
else printf ("%d", mtx[x][y]);
}
printf ("\n");
}
int odd[row], even[row]; //Make a var to store odd/even value each row
for (int x=0; x<row; x++)
{
odd[x]=even[x]=0; //Set to 0 before doing an operation, for safety
for (int y=0; y<col; y++)
{
if (mtx[x][y]%2) odd[x]++; //If it is odd, odd[which_row] incremented
else even[x]++; //Else, even gets incremented
}
printf ("%d %d\n", even[x], odd[x]);
}
int temp;
for (int x=0; x<row-1; x++)
{
for (int y=x+1; y<row; y++)
{
if (even[x]<even[y]) //Same "concept" like bubble sort
{
for (int z=0; z<col; z++)
{
temp=mtx[x][z]; //Swapping the content of the matrix
mtx[x][z]=mtx[y][z];
mtx[y][z]=temp;
}
temp=even[x]; //Swap the value of even[x]
even[x]=even[y];
even[y]=temp;
}
}
}
//Print the result
for (int x=0; x<row; x++)
{
for (int y=0; y<col; y++)
{
if (y) printf (" %d", mtx[x][y]);
else printf ("%d", mtx[x][y]);
}
printf ("\n");
}
return 0;
}
Sample IO:
3 3
1 3 5
7 4 6
2 9 3
1 3 5
7 4 6
2 9 3
0 3
2 1
1 2
7 4 6
2 9 3
1 3 5
user3386109's idea:
for (int x=maxEven; x>=0; x--)
{
for (int y=0; y<row; y++)
{
if (even[y]==x)
{
for (int z=0; z<col; z++)
{
if (z) printf (" %d", mtx[y][z]);
else printf ("%d", mtx[y][z]);
}
printf ("\n");
break;
}
}
}