CLRS7

gycg · Sep 15, 2016 · aee409d · aee409d
1 parent 083d6d5
commit aee409d
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diff --git a/quick_sort.py b/quick_sort.py
@@ -0,0 +1,19 @@
+def partition(A, p, r):
+    x = A[r]
+    i = p-1
+    for j in xrange(p, r):
+        if A[j] <= x:
+            i += 1
+            A[i], A[j] = A[j], A[i]
+    A[i+1], A[r] = A[r], A[i+1]
+    return i+1
+
+def quicksort(A, p, r):
+    if p < r:
+        q = partition(A, p, r)
+        quicksort(A, p, q-1)
+        quicksort(A, q+1, r)
+
+A = [2, 8, 7, 1, 3, 5, 6, 4]
+quicksort(A, 0, 7)
+print A
diff --git a/randomized_quicksort.py b/randomized_quicksort.py
@@ -0,0 +1,25 @@
+def partition(A, p, r):
+    x = A[r]
+    i = p-1
+    for j in xrange(p, r):
+        if A[j] <= x:
+            i += 1
+            A[i], A[j] = A[j], A[i]
+    A[i+1], A[r] = A[r], A[i+1]
+    return i+1
+
+def randomized_partition(A, p, r):
+    from random import randrange
+    i = randrange(p, r+1, 1)
+    A[r], A[i] = A[i], A[r]
+    return partition(A, p, r)
+
+def randomized_quicksort(A, p, r):
+    if p < r:
+        q = randomized_partition(A, p, r)
+        randomized_quicksort(A, p, q-1)
+        randomized_quicksort(A, q+1, r)
+
+A = [2, 8, 7, 1, 3, 5, 6, 4]
+randomized_quicksort(A, 0, 7)
+print A