Why is this recursive selection sort not working - c++

Question

I tried to run the code but it just gets stuck. NO error no warning nothing.Is there a better way to write a recursive selection sort?
#include <iostream>
using namespace std;
void scan(int *arr, int size){
for(int i = 0; i < size; i++){
cin >> arr[i];
}
}
void print(int *arr, int size){
for(int i = 0; i < size; i++){
cout << arr[i] << " ";
}
cout << "\n";
}
void swap(int *p1, int *p2){
int temp = *p1;
*p1 = *p2;
*p2 = temp;
}
void insertion(int *arr, int size){
if(size <= 1)return;
int i, max = size - 1;
for(int i = 0; i < size; i++){
if(arr[i] > arr[max])max = i;
}
swap(&arr[max], &arr[i]);
insertion(arr, size - 1);
}
int main(){
int *arr;
int size;
cout << "Enter the size of the array - ";
cin >> size;
arr = (int*)malloc(size*sizeof(int));
cout << "Enter the elements of the array - ";
scan(arr, size);
print(arr, size);
insertion(arr, size);
print(arr, size);
}
I feel like there is something wrong with the base case of the recursion. How do you generally solve these types of problems.

Answer 1

There was 1 small problem in your code. When you call the swap function in the insertion function you have to call it with &arr[max] and &arr[size-1], you can also use i-1, as the value of i is size here.
Code Attached for insertion function
void insertion(int *arr, int size){
if(size <= 1)return;
int i, maxIndex = 0;
for(i = 0; i < size; i++){
if(arr[i] > arr[maxIndex]) maxIndex = i;
}
swap(&arr[maxIndex], &arr[size-1]);
insertion(arr, size - 1);
}
The way to debug are many, you can learn to use the gnu debugger which is gdb or use print statements to find out where your code is going wrong.