Created
March 3, 2013 06:29
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quicksort - gets it sorted but wastes time
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def quicksortTest(A,p,r): | |
print A | |
if (p<r): | |
q = partition(A,p,r) | |
print "********************************************** q=, ", q, " r=", r | |
quicksortTest(A,q+1,r) | |
if (p==r): | |
print "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! p = r", p, r | |
q = partition(A,p,r) | |
quicksortTest(A,0,q-1) | |
#quicksortTest(A,p,q) | |
def partition(A, p, r): | |
x = A[p] | |
print "Pivot: ", x | |
i = p-1 | |
j = r+1 | |
while True: | |
while True: | |
j -= 1 | |
print "working from the end, comparing", A[j], " and ", x | |
if (A[j]<=x): | |
print A[j], " <= ", x | |
break | |
while True: | |
i += 1 | |
print "working from the beginning, comparing", A[i], " and ", x | |
if (A[i]>=x): | |
print A[i], " >= ", x | |
break | |
if (i<j): | |
print "Switching, ", A[i], " with ", A[j] | |
A[i], A[j] = A[j], A[i] | |
print A | |
else: | |
print i, " is not less than ", j | |
return j | |
def hoare(a, p, r): | |
x = a[p] | |
i, j = p-1, r+1 | |
while True: | |
while True: | |
j -= 1 | |
if a[j] <= x: | |
break | |
while True: | |
i += 1 | |
if a[i] >= x: | |
break | |
if i < j: | |
print "Switching, ", a[i], " with ", a[j] | |
a[i], a[j] = a[j], a[i] | |
else: | |
return j | |
Array = [2,8,7,1,3,5,6,4] | |
p = 0 | |
r = len(Array) - 1 | |
print "*** START ***" | |
quicksortTest(Array,p,r) | |
print "*** END ***" |
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