Replacing nested for loops in C++ - c++

Question

So I wrote this code but the problem is I have a restriction in my assignment that I can't use nested for loops in my code.
#include<iostream>
using namespace std;
void Exchange(int* a, int* b) {
int var;
var = *a; //For swapping or exchanging values. O_o
*a = *b;
*b = var;
}
void Algorithm(int array[], int nerd) {
int i, j, k; //This is the actual algorithm which is required. ;)
for (i = 0; i < nerd;) {
for (j = i + 1; j < nerd; j++) {
if (array[j] < array[j - 1])
Exchange(&array[j], &array[j - 1]);
}
nerd--;
for (k = nerd - 1; k > i; k--) {
if (array[k] < array[k - 1])
Exchange(&array[k], &array[k - 1]);
}
i++;
}
}
int main() {
int n, i;
cout << "\nEnter the count of numbers for the algorithm: ";
cin >> n;
int arr[10];
for (i = 0; i < n; i++) {
cout << "Enter number " << i + 1 << ": ";
cin >> arr[i];
}
Algorithm(arr, n);
cout << "\nFinal Data you entered (after the algorithm performed)";
for (i = 0; i < n; i++)
cout << " -> " << arr[i];
return 0;
}

Answer 1

One loop using modulus on the one loop counter:
#include <utility> // std::swap
void Algorithm(int array[], int nerd) {
int max = nerd * (nerd - 1);
for(int i = 1; i < max; ++i) {
// If at start of the removed inner loop, skip i % nerd == 0
if(i % nerd == 0) ++i;
if (array[i % nerd] < array[(i-1) % nerd])
std::swap(array[i % nerd], array[(i - 1) % nerd]);
}
}
Demo
Without modulus, decreasing nerd and restarting with i = 1 each time i == nerd:
void Algorithm(int array[], int nerd) {
for(int i = 1; nerd > 1; ++i) {
if(i == nerd) { // start of the removed inner loop
--nerd; // the highest number will already be in place
i = 1;
}
if (array[i] < array[i - 1])
std::swap(array[i], array[i - 1]);
}
std::cout << "ted " << nerd << '\n';
}
Demo
An alternative to quit looping early if no swaps were made last round:
void Algorithm(int array[], int nerd) {
if(nerd < 2) return;
bool done = true;
for(int i = 1;; ++i) {
if(i % nerd == 0) {
if(done) break;
++i;
done = true;
}
if (array[i % nerd] < array[(i-1) % nerd]) {
std::swap(array[i % nerd], array[(i-1) % nerd]);
done = false;
}
}
}
Demo
The alternative without modulus and with the decreasing nerd optimization:
void Algorithm(int array[], int nerd) {
if(nerd < 2) return;
bool done = true;
for(int i = 1;; ++i) {
if(i == nerd) {
if(done || --nerd == 1) break;
i = 1;
done = true;
}
if (array[i] < array[i - 1]) {
std::swap(array[i], array[i - 1]);
done = false;
}
}
}
Demo