Question

code is simple

def bubble_sort(l):
    for i in xrange(0, len(l)-1) :
        for n in xrange(0, len(l)) :
            if l[i] > l[i+1] :
                l[i], l[i+1] = l[i+1], l[i]

lst = [[1, 8, 2], [3, 2, 5], [2, 13, 3], [2, 5, 5], [2, 5, 6], [5, 11, 6], [5, 5, 6]]
print(lst)
bubble_sort(lst)
print(lst)

---

result:

[[1, 8, 2], [3, 2, 5], [2, 13, 3], [2, 5, 5], [2, 5, 6], [5, 11, 6], [5, 5, 6]]
[[1, 8, 2], [2, 13, 3], [2, 5, 5], [2, 5, 6], [3, 2, 5], [5, 5, 6], [5, 11, 6]]

the sort is not correct.

why?

Answer 1

The problem is that you’re making only one iteration, while in bubble sort you should iterate over and over again until there are no swapped pairs anymore. Like this:

def bubble_sort(l):
    ok = False

    while not ok:
        ok = True
        for i in range(len(l) - 1):
            if l[i] > l[i+1]:
                l[i], l[i+1] = l[i+1], l[i]
                ok = False