mergeSort

package POJ;

public class Main {

    /**
     * 
     * MergeSort
     * 
     */
    public static void main(String[] args) {
        Main so = new Main();
        int[] list = { 6, 4, 2, 3, 1, 5, 10, 4, 9, 8, 11, 7 };
        int[] result = so.mergeSort(list);
        for (int a : result)
            System.out.println(a);
    }

    public int[] mergeSort(int[] list) {
        int[] helper = new int[list.length];
        mergeSort(list, helper, 0, list.length - 1);
        return list;
    }

    private void mergeSort(int[] list, int[] helper, int low, int high) {
        // TODO Auto-generated method stub
        if (low < high) {
            int mid = (high + low) / 2;
            mergeSort(list, helper, low, mid);
            mergeSort(list, helper, mid + 1, high);
            merge(list, helper, low, mid, high);
        }
    }

    private void merge(int[] list, int[] helper, int low, int mid, int high) {
        // TODO Auto-generated method stub
        for (int i = low; i <= high; i++) {
            helper[i] = list[i];
        }
        int helperLeft = low;
        int helperRight = mid + 1;
        int current = low;
        while (helperLeft <= mid && helperRight <= high) {
            if (helper[helperLeft] <= helper[helperRight]) {
                list[current] = helper[helperLeft];
                helperLeft++;
            } else {
                list[current] = helper[helperRight];
                helperRight++;
            }
            current++;
        }
        int remaining = mid - helperLeft;
        for (int i = 0; i <= remaining; i++) {
            list[current + i] = helper[helperLeft + i];
        }
    }
}