hapter4-binary-search-algorithm
二分查找
普通二分与变种
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28def binarySearch():
nums, key = [1,2,3,4,5], 3
def common():
left, right = 0, len(nums)
while(left <= right):
mid = left + (right-left)//2 #mid=(l + h)//2方式 可能出现加法溢出，也就是说加法的结果大于整型能够表示的范围，比如5 5 5
if key == nums[mid]:
return mid
if key > nums[mid]:
left = mid + 1
else:
right = mid - 1
return False
print(common())
#变种就是对边界进行判断
def variety():
left, right = 0, len(nums)
while (left < right):
mid = left + (right - left) // 2 # mid=(l + h)//2方式 可能出现加法溢出，也就是说加法的结果大于整型能够表示的范围，比如5 5 5
if key > nums[ mid ]:
left = mid + 1
else:
right = mid
return left
index = variety()
print(nums[index])
binarySearch()
