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January 27, 2017 14:22
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queue implemented with a pair of stacks
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class staq: | |
def __init__(self, stack = []): | |
self.enqstk = stack | |
self.deqstk = [] | |
def _swap(self): | |
if len(self.deqstk) == 0: | |
while len(self.enqstk) > 0: | |
_pus(self.deqstk, _pop(self.enqstk)) | |
def enq(self, item): | |
_pus(self.enqstk, item) | |
def deq(self): | |
self._swap() | |
return _pop(self.deqstk) | |
def __str__(self): | |
return "%s -> %s" % (self.enqstk,self.deqstk) | |
def __repr__(self): | |
return str(self) | |
def _pop(stack): | |
out = stack[-1] | |
stack[:] = stack[:-1] | |
return out | |
def _pus(stack, item): | |
stack += [item] | |
if __name__ == "__main__": | |
q = staq([1,2,3]) | |
print("q = staq([1,2,3]) : %s" % (q,)) | |
print("q.deq() -> %s : %s" % (q.deq(), q)) | |
q.enq(4) | |
print("q.enq(4) : %s" % (q,)) | |
print("q.deq() -> %s : %s" % (q.deq(), q)) | |
print("q.deq() -> %s : %s" % (q.deq(), q)) | |
print("q.deq() -> %s : %s" % (q.deq(), q)) |
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