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fix IndexError when E. bigger than others

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chenzhejia 2019-04-18 16:16:39 +08:00 committed by GitHub
parent 9d072236b9
commit d0c8c828dc
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1 changed files with 33 additions and 15 deletions
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48
python/16_bsearch/bsearch_variants.py
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@ -1,5 +1,6 @@
""" """
Author: Wenru Author: Wenru
Fix: nzjia
""" """
from typing import List from typing import List
@ -16,7 +17,11 @@ def bsearch_left(nums: List[int], target: int) -> int:
low = mid + 1 low = mid + 1
else: else:
high = mid - 1 high = mid - 1
return low if nums[low] == target else -1 if low < len(nums) and nums[low] == target:
return low
else:
return -1
def bsearch_right(nums: List[int], target: int) -> int: def bsearch_right(nums: List[int], target: int) -> int:
"""Binary search of the index of the last element """Binary search of the index of the last element
@ -30,7 +35,10 @@ def bsearch_right(nums: List[int], target: int) -> int:
low = mid + 1 low = mid + 1
else: else:
high = mid - 1 high = mid - 1
return high if nums[high] == target else -1 if high >= 0 and nums[high] == target:
return high
else:
return -1
def bsearch_left_not_less(nums: List[int], target: int) -> int: def bsearch_left_not_less(nums: List[int], target: int) -> int:
@ -45,7 +53,10 @@ def bsearch_left_not_less(nums: List[int], target: int) -> int:
low = mid + 1 low = mid + 1
else: else:
high = mid - 1 high = mid - 1
return low if low < len(nums) else -1 if low < len(nums) and nums[low] >= target:
return low
else:
return -1
def bsearch_right_not_greater(nums: List[int], target: int) -> int: def bsearch_right_not_greater(nums: List[int], target: int) -> int:
"""Binary search of the index of the last element """Binary search of the index of the last element
@ -59,19 +70,26 @@ def bsearch_right_not_greater(nums: List[int], target: int) -> int:
low = mid + 1 low = mid + 1
else: else:
high = mid - 1 high = mid - 1
return high if high > 0 else -1 if high >= 0 and nums[high] <= target:
return high
else:
return -1
if __name__ == "__main__": if __name__ == "__main__":
import bisect a = [1, 1, 2, 3, 4, 6, 7, 7, 7, 7, 10, 22]
a = [0, 1, 1, 2, 3, 4, 5, 6, 6, 7, 8, 8, 10, 10, 10] print(bsearch_left(a, 0) == -1)
b = [11, 12, 12, 13, 14, 14, 15, 15] print(bsearch_left(a, 7) == 6)
print(bisect.bisect_left(a, 10) == bsearch_left(a, 10)) print(bsearch_left(a, 30) == -1)
print(bisect.bisect_right(a, 10))
print(bisect.bisect_right(a, 6)-1 == bsearch_right(a, 6))
print(bisect.bisect_right(b, 14)-1 == bsearch_right(b, 14))
print(bsearch_left_not_less(a, 11)) print(bsearch_right(a, 0) == -1)
print(bsearch_right_not_greater(b, 12)) print(bsearch_right(a, 7) == 9)
print(bsearch_right_not_greater(b, 10)) print(bsearch_right(a, 30) == -1)
print(bsearch_right_not_greater(b, 17))
print(bsearch_left_not_less(a, 0) == 0)
print(bsearch_left_not_less(a, 5) == 5)
print(bsearch_left_not_less(a, 30) == -1)
print(bsearch_right_not_greater(a, 0) == -1)
print(bsearch_right_not_greater(a, 6) == 5)
print(bsearch_right_not_greater(a, 30) == 11)