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from libc.stdlib cimport malloc, free
cdef struct Node:
Node *left
Node *right
int item
cdef Node *make_tree(int item, int depth):
cdef Node *t = <Node*>malloc(sizeof(Node))
t.item = item
if depth:
depth -= 1
item <<= 1
t.left = make_tree(item - 1, depth)
t.right = make_tree(item, depth)
else:
t.left = NULL
t.right = NULL
return t
cdef int check_tree(Node* t):
cdef int tmp
if t.left:
tmp = t.item + check_tree(t.left) - check_tree(t.right)
else:
tmp = t.item
free(t)
return tmp
def main(int n):
# By definition, trees can't have cycles. However, Python's garbage
# collector will do lots of wasteful tree traversals to try to collect
# circular references. Normal reference counting still happens.
#import gc
#gc.disable()
cdef int min_depth, max_depth, stretch_depth, depth
min_depth = 4
max_depth = max(min_depth + 2, n)
stretch_depth = max_depth + 1
cdef int i, iterations
cdef int check
print "stretch tree of depth %d\t check:" % stretch_depth, check_tree(make_tree(0, stretch_depth))
long_lived_tree = make_tree(0, max_depth)
iterations = 1 << max_depth
for depth in xrange(min_depth, stretch_depth, 2):
check = 0
for i in xrange(1, iterations + 1):
check += check_tree(make_tree(i, depth))
check += check_tree(make_tree(-i, depth))
print "%d\t trees of depth %d\t check:" % (iterations * 2, depth), check
iterations >>= 2
print "long lived tree of depth %d\t check:" % max_depth, check_tree(long_lived_tree)
if __name__ == '__main__':
import sys
main(int(sys.argv[1]))
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