快速排序和归并排序模板（Java实现）

快速排序

public static void quick_sort(int[] q, int l, int r) {
    if (l >= r)  return;

    int i = l - 1, j = r + 1, x = q[l + r >> 1];
    while (i < j) {
        do i ++; while (q[i] < x);
        do j --; while (q[j] > x);
        if (i < j) {
            int t = q[i];
            q[i] = q[j];
            q[j] = t;
        }
    }
    quick_sort(q, l, j);
    quick_sort(q, j + 1, r);
}

归并排序

public static void merge_sort(int[] q, int l, int r) {
    if (l >= r) return;

    int mid = l + r >> 1;
    merge_sort(q, l, mid);
    merge_sort(q, mid + 1, r);

    int k = 0, i = l, j = mid + 1;
    int[] tmp = new int[q.length];
    while (i <= mid && j <= r)
        if (q[i] < q[j]) tmp[k ++] = q[i ++];
        else tmp[k ++] = q[j ++];

    while (i <= mid) tmp[k ++] = q[i ++];
    while (j <= r) tmp[k ++] = q[j ++];

    for (i = l, j = 0; i <= r; i ++, j ++ ) q[i] = tmp[j];
}

测试代码

public static void main(String[] args) {
    final int size = 10;
    int[] a = new int[size];

    // 快速排序
    for (int i = 0; i < size; i ++) {
        a[i] = (int) (Math.random() * 100);
    }
    quick_sort(a, 0, a.length - 1);
    for (int i : a) {
        System.out.print(i + " ");
    }

    System.out.println();

    //归并排序
    for (int i = 0; i < size; i ++) {
        a[i] = (int) (Math.random() * 100);
    }
    merge_sort(a, 0, a.length - 1);
    for (int i : a) {
        System.out.print(i + " ");
    }
}