How do I change postition of number in 2d array in c++? - c++

Question

I tried to find the biggest number in every row of a 2D array, and to put it on diametrum. I did that, but I now want to replace that number, not just declare them on diametrum. How do I change the place of numbers for my case? Here's code:
#include<iostream>
using namespace std;
int mac(int b[],int n)
{
int i,max,c=0;
max=b[0];
for(i=0;i<n;i++)
{
if(max<b[i]) {max=b[i];c=i;}
}
return c;
}
int main()
{
int i,j,n;
int c;
int a[10][10],b[10];
cin>>n;
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
{
cin>>a[i][j];
cin.ignore();
}
}
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
b[j]=a[i][j];
c=mac(b,n);
/*Place where i should change something*/
a[i][i]=a[i][c];
}
for(i=0;i<n;i++)
{
for(j=0;j<n;j++)
{
cout<<a[i][j];
}
cout<<endl;
}
return 0;
}

Answer 1

You need to do swap. So you have to define one temporary variable to save actual value from [i][i]. Then overwrite position [i][i] with max value and at the end you need place temp value back to position where you found max value.
/*Place where i should change something*/
int temp = a[i][i];
a[i][i] = a[i][c];
a[i][c] = temp;

Answer 2

Assuming that when n = 3, and input is 1 2 3 4 5 6 7 8 9 the output should be 321 465 789
The code should be
#include <iostream>
#include <vector>
using namespace std;
int main() {
vector< vector<int> > a;
size_t n;
cout<<"Enter number of value for N: ";
cin>>n;
a.reserve(n);
for (size_t i = 0; i<n;i++) {
a[i].reserve(n);
for (size_t j =0 ; j<n;j++) {
cin>>a[i][j];
}
}
for (size_t i = 0; i<n;i++) {
size_t index = 0;
int max = INT_MIN;
for (size_t j =0 ; j<n;j++) {
if (a[i][j] >= max) {
max = a[i][j];
index = j;
}
}
a[i][index] = a[i][i];
a[i][i] = max;
}
cout<<"\nOutput\n";
for (size_t i = 0; i<n;i++) {
for (size_t j =0 ; j<n;j++) {
cout<<a[i][j]<<" ";
}
cout<<endl;
}
}