代码： 全选
def search_binary(xs, target):
""" Find and return the index of key in sequence xs """
lb = 0
ub = len(xs)
while True:
if lb == ub: # If region of interest (ROI) becomes empty
return -1
# Next probe should be in the middle of the ROI
mid_index = (lb + ub) // 2
# Fetch the item at that position
item_at_mid = xs[mid_index]
# print("ROI[{0}:{1}](size={2}), probed='{3}', target='{4}'"
# .format(lb, ub, ub-lb, item_at_mid, target))
# How does the probed item compare to the target?
if item_at_mid == target:
return mid_index # Found it!
if item_at_mid < target:
lb = mid_index + 1 # Use upper half of ROI next time
else:
ub = mid_index # Use lower half of ROI next time
