How to find the values being swapped in two different arrays? - c++

Question

I am suppose to swap an array with the odds in one array and the evens in another while keeping track of the count and the values being swapped.
{2, 3, 6}
{1, 4, 7}
will become
{1, 3, 7}
{2, 4, 6}
With 2 swaps, and the values being swapped are
1 &2, 6 & 7.
int main() {
int a1[3] = { 2, 3, 6 };
int a2[3] = { 1, 4, 7 };
int i;
int swapcount = 0;
int swapvalue;
std::cout << "Before swap:\n" << endl;
std::cout << "Array 1:\n" << endl;
for (int i = 0; i < 3; i++) {
cout << " " << a1[i] << endl;
}
std::cout << "Array 2:\n" << endl;
for (int i = 0; i < 3; i++) {
std::cout << " " << a2[i] << endl;
}
for (int i = 0; i < 3; i++) {
if (a1[i] % 2 != 1) {
swapcount++;
int temp = a1[i];
a1[i] = a2[i];
a2[i] = temp;
swapvalue = i;
}
}
std::cout << "After swap:\n" << endl;
std::cout << "Array 1:\n" << endl;
for (int i = 0; i < 3; i++) {
std::cout << " " << a1[i] << endl;
}
std::cout << "Array 2:\n" << endl;
for (int i = 0; i < 3; i++) {
std::cout << " " << a2[i] << endl;
}
std::cout << "swap count: " << swapcount << endl;
std::cout << "swap value: " << swapvalue << endl;
}
So far, I have gotten the swap and counter to work but I cannot seem to figure out:
How to find and store the individual values of the elements that are swapped? (I can get only one value to show.)
Can I get any hints on how to all grab the values? I am not allowed to use any additional libraries except for the input and output streams. Thanks ahead of time.

Answer 1

Create an auxiliary array swapbool, set boolean = 1 if a swap is done.
#include<iostream>
using namespace std;
int main() {
int a1[3] = { 2, 3, 6 };
int a2[3] = { 1, 4, 7 };
int swapbool[3] = {0,0,0};
int i;
int swapcount = 0;
int swapvalue;
std::cout << "Before swap:\n" << endl;
std::cout << "Array 1:\n" << endl;
for (int i = 0; i < 3; i++) {
cout << " " << a1[i] << endl;
}
std::cout << "Array 2:\n" << endl;
for (int i = 0; i < 3; i++) {
std::cout << " " << a2[i] << endl;
}
for (int i = 0; i < 3; i++) {
if (a1[i] % 2 != 1) {
swapcount++;
int temp = a1[i];
a1[i] = a2[i];
a2[i] = temp;
// swapvalue = i;
swapbool[i]=1;
}
}
std::cout << "After swap:\n" << endl;
std::cout << "Array 1:\n" << endl;
for (int i = 0; i < 3; i++) {
std::cout << " " << a1[i] << endl;
}
std::cout << "Array 2:\n" << endl;
for (int i = 0; i < 3; i++) {
std::cout << " " << a2[i] << endl;
}
std::cout << "swap count: " << swapcount << endl;
for (int i = 0; i < 3; i++) {
if(swapbool[i] == 1)
{
std::cout << "swapvalue1-> " << a2[i] << endl;
std::cout << "swapvalue2-> " << a1[i] << endl;
}
}
//std::cout << "swap value: " << swapvalue << endl;
}

Answer 2

There are a lot of ways of doing it. The simplest solution is to store them in std::vector of std::pair:
std::vector<std::pair<int, int>> swapvalues;
And then inserting:
swapvalues.emplace_back(val1, val2);
By the way, in your code you store index, not values. If you want to store indices, use only std::vector of integers.

Answer 3

How to find the individual values of the elements that are swapped?
When you swap the elements store their indexes:
int swappedValuesIndex[];
for (int i = 0; i < 3; i++) {
if (a1[i] % 2 != 1) {
// store swapped values' index
swappedValuesIndex[swapcount] = i;
swapcount++;
int temp = a1[i];
a1[i] = a2[i];
a2[i] = temp;
swapvalue = i;
}
}
// print swapped values
for (int i = 0; i < swapcount; i++){
cout <<"a1["<< swappedValuesIndex[i] <<"]"<< a1[swappedValuesIndex[i]] <<'\n';
cout <<"a2["<< swappedValuesIndex[i] <<"]"<< a2[swappedValuesIndex[i]] <<'\n';
}