mirror of
https://github.com/python/cpython.git
synced 2024-11-21 12:59:38 +01:00
119 lines
3.3 KiB
Python
119 lines
3.3 KiB
Python
"""Bisection algorithms."""
|
|
|
|
|
|
def insort_right(a, x, lo=0, hi=None, *, key=None):
|
|
"""Insert item x in list a, and keep it sorted assuming a is sorted.
|
|
|
|
If x is already in a, insert it to the right of the rightmost x.
|
|
|
|
Optional args lo (default 0) and hi (default len(a)) bound the
|
|
slice of a to be searched.
|
|
|
|
A custom key function can be supplied to customize the sort order.
|
|
"""
|
|
if key is None:
|
|
lo = bisect_right(a, x, lo, hi)
|
|
else:
|
|
lo = bisect_right(a, key(x), lo, hi, key=key)
|
|
a.insert(lo, x)
|
|
|
|
|
|
def bisect_right(a, x, lo=0, hi=None, *, key=None):
|
|
"""Return the index where to insert item x in list a, assuming a is sorted.
|
|
|
|
The return value i is such that all e in a[:i] have e <= x, and all e in
|
|
a[i:] have e > x. So if x already appears in the list, a.insert(i, x) will
|
|
insert just after the rightmost x already there.
|
|
|
|
Optional args lo (default 0) and hi (default len(a)) bound the
|
|
slice of a to be searched.
|
|
|
|
A custom key function can be supplied to customize the sort order.
|
|
"""
|
|
|
|
if lo < 0:
|
|
raise ValueError('lo must be non-negative')
|
|
if hi is None:
|
|
hi = len(a)
|
|
# Note, the comparison uses "<" to match the
|
|
# __lt__() logic in list.sort() and in heapq.
|
|
if key is None:
|
|
while lo < hi:
|
|
mid = (lo + hi) // 2
|
|
if x < a[mid]:
|
|
hi = mid
|
|
else:
|
|
lo = mid + 1
|
|
else:
|
|
while lo < hi:
|
|
mid = (lo + hi) // 2
|
|
if x < key(a[mid]):
|
|
hi = mid
|
|
else:
|
|
lo = mid + 1
|
|
return lo
|
|
|
|
|
|
def insort_left(a, x, lo=0, hi=None, *, key=None):
|
|
"""Insert item x in list a, and keep it sorted assuming a is sorted.
|
|
|
|
If x is already in a, insert it to the left of the leftmost x.
|
|
|
|
Optional args lo (default 0) and hi (default len(a)) bound the
|
|
slice of a to be searched.
|
|
|
|
A custom key function can be supplied to customize the sort order.
|
|
"""
|
|
|
|
if key is None:
|
|
lo = bisect_left(a, x, lo, hi)
|
|
else:
|
|
lo = bisect_left(a, key(x), lo, hi, key=key)
|
|
a.insert(lo, x)
|
|
|
|
def bisect_left(a, x, lo=0, hi=None, *, key=None):
|
|
"""Return the index where to insert item x in list a, assuming a is sorted.
|
|
|
|
The return value i is such that all e in a[:i] have e < x, and all e in
|
|
a[i:] have e >= x. So if x already appears in the list, a.insert(i, x) will
|
|
insert just before the leftmost x already there.
|
|
|
|
Optional args lo (default 0) and hi (default len(a)) bound the
|
|
slice of a to be searched.
|
|
|
|
A custom key function can be supplied to customize the sort order.
|
|
"""
|
|
|
|
if lo < 0:
|
|
raise ValueError('lo must be non-negative')
|
|
if hi is None:
|
|
hi = len(a)
|
|
# Note, the comparison uses "<" to match the
|
|
# __lt__() logic in list.sort() and in heapq.
|
|
if key is None:
|
|
while lo < hi:
|
|
mid = (lo + hi) // 2
|
|
if a[mid] < x:
|
|
lo = mid + 1
|
|
else:
|
|
hi = mid
|
|
else:
|
|
while lo < hi:
|
|
mid = (lo + hi) // 2
|
|
if key(a[mid]) < x:
|
|
lo = mid + 1
|
|
else:
|
|
hi = mid
|
|
return lo
|
|
|
|
|
|
# Overwrite above definitions with a fast C implementation
|
|
try:
|
|
from _bisect import *
|
|
except ImportError:
|
|
pass
|
|
|
|
# Create aliases
|
|
bisect = bisect_right
|
|
insort = insort_right
|