def get_unique_adjacent(string: str) -> Optional[str]:
length = len(string)
freq = {}
if length == 0:
return string
for i in range(length):
if string[i] not in freq:
freq[string[i]] = 0
freq[string[i]] += 1
sorted_freq = sorted(freq.items(), key=lambda x: x[1], reverse=True)
queue = Queue()
[queue.enqueue(item) for item in sorted_freq]
result = ""
if length % 2 == 0 and sorted_freq[0][1] > length // 2:
return None
elif length % 2 == 1 and sorted_freq[0][1] > (length // 2) + 1:
return None
while not queue.is_empty():
if len(queue) == 1:
elem, freq = queue.peek()
if freq == 2:
result = elem + result + elem
break
elif freq == 1:
if result[-1] != elem:
result += elem
else:
result = elem + result
break
return None
elem1, freq1 = queue.peek()
elem2, freq2 = None, None
if len(queue) > 1:
elem2, freq2 = queue[1]
result += elem1 + elem2
queue[0] = elem1, freq1 - 1
if len(queue) > 1:
queue[1] = elem2, freq2 - 1
if len(queue) > 1 and queue[1][1] == 0:
queue.dequeue()
if len(queue) > 0 and queue[0][1] == 0:
queue.dequeue()
return result
def sorted_merge(A: list, B: list):
"""
Time: O(A + B) actually O(2A + 2B), copying then reading back, with O(min(A, B)) comparisons in the worst case
Space: O(n)
:param A:
:param B:
:return:
"""
p1, p2 = 0, len(A) - len(B)
stack_A = Queue(iterable=A[:p2])
stack_B = Queue(iterable=B)
for i in range(len(A)):
if stack_A.is_empty():
A[i] = stack_B.pop()
elif stack_B.is_empty():
A[i] = stack_A.pop()
elif stack_A.peek() <= stack_B.peek():
A[i] = stack_A.pop()
else:
A[i] = stack_B.pop()
return A
from DataStructures.Queue import Queue # Setup q = Queue(1) q.enqueue(2) q.enqueue(3) # Test peek # Should be 1 print(q.peek()) # Test dequeue # Should be 1 print(q.dequeue()) # Test enqueue q.enqueue(4) # Should be 2 print(q.dequeue()) # Should be 3 print(q.dequeue()) # Should be 4 print(q.dequeue()) q.enqueue(5) # Should be 5 print(q.peek())
import sys
sys.path.append("../")
from DataStructures.Queue import Queue
try:
print("\nStart Queue Tests ..")
# Setup
q = Queue(1)
q.enqueue(2)
q.enqueue(3)
# Test peek
# Should be 1
assert q.peek() == 1
# Test dequeue
# Should be 1
assert q.dequeue() == 1
# Test enqueue
q.enqueue(4)
# Should be 2
assert q.dequeue() == 2
# Should be 3
assert q.dequeue() == 3
# Should be 4
assert q.dequeue() == 4
q.enqueue(5)
# Should be 5