Question

I can’t figure out why this isn’t working.

public class InsertionSort {

    public static void main(String[] args) {

        int x[] = { 9, 5, 8, 4, 3, 0, 6, 7, 2, 1 };
        int[] result = InsertionSortMethod(x);

        for (int z = 0; z < x.length; z++) {
            System.out.print(x[z] + " ");
        }
    }

    public static int[] InsertionSortMethod(int x[]){
        for (int a = 0; a < x.length; a++) {
            int divider = a;
            if(divider > 0 & divider < x.length){
                if(x[divider] < x[0]){
                    int temp = x[divider];
                    for(int c = divider; c > 0; c--){
                        x[c] = x[c-1];
                    }
                    x[0] = temp;
                }
                if(x[divider] > x[divider-1]){
                    x[divider] = x[divider];
                }
                else{
                    for(int b = divider-1; b > 0; b--){
                        if(x[divider] < x[b]){
                            int temp = x[divider];
                            x[divider] = x[b];
                            x[b] = temp;
                        }
                    }
                }
            }
        }
        return x;
    }

}

Answer 1

You say you want to do it yourself, so just this:

for(int b = divider-1; b > 0; b--){
    if(x[divider] < x[b]){
        int temp = x[divider];
        x[divider] = x[b];
        x[b] = temp;
    }
}

If the part of the array with indices smaller than divider is already sorted, and x[divider] is between x[0] and x[1], for example (and divider larger than 3, say), then x[divider] < x[divider-1] and in that loop is immediately swapped into position divider-1. But then the value at index divider has just become larger than x[b] for 0 <= b <= divider-2 and no further swaps are done. One possible way to deal with that is to update divider after each swap, divider = b; inside the if.