Recursion_ipynb_2_

public static int factorial(int target) {
    if (target > 0){
        return target * factorial(target-1);
    }
    else if (target == 0){
        return 1; //apparently "0! = 1"
    }
    else {
        return -1; //not a possible value
    }
}

System.out.println(factorial(-100));

-1

popcorn hack #2 (sumArray)

public static int sumArray(int[] arr, int index) { 
    if(index < arr.length){
        return arr[index]+sumArray(arr,index+1);
    }
    return 0;
} 

int[] array = {0,1,2,3,4};
System.out.println(sumArray(array,0));

0

popcorn hack #3 selection sort

public static int[] selctionSort(int[] arr, int index, int max) { 
    if(index <= 1){ return selctionSort(arr,index+1,arr[0]);};

    int[] temp = new int[arr.length];

    int offset = 0;
    if(arr[index] >= max){
        temp[0] = arr[index];
        temp[1] = arr[0];
        arr[0] = arr[1];
        arr[1] = temp[1];
        arr[index] = arr[0];

        offset = 1;
    }
    

    for(int i = offset; i<temp.length;i++){
        temp[i]=arr[i];
    }

    System.out.println(Arrays.toString(temp));
    if (index + 1 == arr.length){return temp;};

    return selctionSort(temp,index + 1,temp[0]);
}

int[] array = {7,2,5,6};

System.out.println(Arrays.toString(selctionSort(array,0,array[0])));

[7, 2, 5, 6]
[7, 2, 5, 6]
[7, 2, 5, 6]