/
binary_search.py
61 lines (53 loc) · 1.46 KB
/
binary_search.py
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import random
def binary_search(array, elem, start=None, end=None):
if start is None:
start = 0
if end is None:
end = len(array)
m = (start + end) // 2
if start > end:
return -1
if array[m] == elem:
return m
if elem < array[m]:
return binary_search(array, elem, start, m - 1)
return binary_search(array, elem, m + 1, end)
def binary_search_iter(array, elem):
start = 0
end = len(array)
while start <= end:
m = (start + end) // 2
if array[m] == elem:
return m
if elem < array[m]:
end = m - 1
else:
start = m + 1
return -1
def binary_search_min_index(array, elem, start=None, end=None):
if start is None:
start = 0
if end is None:
end = len(array)
m = (start + end) // 2
if start > end:
return -1
if array[m] == elem:
for j in reversed(range(m+1)):
print(j, array[j], elem)
if array[j] == elem:
m_ = j
return m_
if elem < array[m]:
return binary_search(array, elem, start, m - 1)
return binary_search(array, elem, m + 1, end)
def main():
a = sorted([random.randrange(10) for i in range(10)])
print(a)
i = random.randrange(len(a))
print(i, a[i])
print(binary_search(a, a[i]))
print(binary_search_iter(a, a[i]))
print(binary_search_min_index(a, a[i]))
if __name__ == "__main__":
main()