归并排序

归并排序

递归

public static void sort1(int[] array, int low, int high) {
        int mid = (low + high) / 2;
        if (low < high) {
            sort(array, low, mid);
            sort(array, mid + 1, high);
            merge1(array, low, mid, high);
        }
    }

private static void merge1(int[] array, int low, int mid, int high) {
        int[] temp = new int[high - low + 1];
        int i = low;
        int j = mid + 1;
        int k = 0;
        while (i <= mid && j <= high) {
            if (array[i] < array[j]) {
                temp[k++] = array[i++];
            } else {
                temp[k++] = array[j++];
            }
        }

        while (i <= mid) {
            temp[k++] = array[i++];
        }

        while (j <= high) {
            temp[k++] = array[j++];
        }

        for (int l = 0; l < temp.length; l++) {
            array[low + l] = temp[l];
        }
    }

归并排序从小到大的将数组进行排序。
非递归

public static void sort2(int[] array) {
        int len = 1;
        while (len <= array.length) {
            for (int i = 0; i + len < array.length; i += len * 2) {
                int low = i;
                int mid = i + len - 1;
                int high = i + len * 2 - 1;
                if (high > array.length - 1)
                    high = array.length - 1;
                merge1(array, low, mid, high);
            }
            len *= 2;
        }
    }