Bubble Sort (Lab 7Opt)

bubblesort.py

def swap(xs, i, j):
    """
    Proj. 5:
    Given the list xs, swap elements i and j.
    
    Modify xs; don't return anything.
    """
    tmp = xs[i]
    xs[i] = xs[j]
    xs[j] = tmp
    
swap_ex = [1,2,3,4]
swap(swap_ex, 0, 2)
assert(swap_ex == [3,2,1,4])

def is_sorted(xs):
    """
    Proj. 5:
    Given a list, return true if it's sorted (no out of order pairs); and False otherwise.
    """
    for i in range(len(xs)-1):
        if xs[i] > xs[i+1]:
            return False
    return True

def swap_out_of_order(xs):
    """
    This is a lot like ``is_sorted`` but instead of complaining,
    we call swap to fix any problems we find!
    
    Modify xs; don't return anything.
    """
    pass
    
swap_ooo = [4,3,2,1]
swap_out_of_order(swap_ooo)
assert(swap_ooo == [3,2,1,4])

swap_ooo2 = [1,3,2,4]
swap_out_of_order(swap_ooo2)
assert(swap_ooo2 == [1,2,3,4])


def bubble_sort(xs):
    """
    To fix up a unsorted list:
    While it's not sorted, call swap_out_of_order!
    
    Modify xs; don't return anything.
    """
    pass
    
shuffled = [7,6,5,4,3,2,1]
bubble_sort(shuffled)
print(shuffled)
assert(is_sorted(shuffled))
assert(shuffled == [1,2,3,4,5,6,7])