Golang 版本

func mergeSort(q []int, l int, r int) {
    if l >= r {
        return
    }

    mid := (r-l)/2+l
    mergeSort(q, l, mid)
    mergeSort(q, mid+1, r)

    i, j, k := l, mid+1, 0
    p := make([]int, r-l+1)

    for i <= mid && j <= r {
        if q[i] <= q[j] {
            p[k] = q[i]
            i++
        } else {
            p[k] = q[j]
            j++
        }
        k++
    }

    for i <= mid {
        p[k] = q[i]
        i++
        k++
    }

    for j <= r {
        p[k] = q[j]
        j++
        k++
    }

    for i, j := l, 0; i <= r; {
        q[i] = p[j]
        i++
        j++
    }
}