You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
42 lines
1.0 KiB
42 lines
1.0 KiB
7 months ago
|
# Lint as: python2, python3
|
||
|
|
# Copyright 2015 The Chromium OS Authors. All rights reserved.
|
||
|
|
# Use of this source code is governed by a BSD-style license that can be
|
||
|
|
# found in the LICENSE file.
|
||
|
|
|
||
|
|
# Utilities for operations on sequences / lists
|
||
|
|
|
||
|
|
|
||
|
|
from __future__ import absolute_import
|
||
|
|
from __future__ import division
|
||
|
|
from __future__ import print_function
|
||
|
|
|
||
|
|
from six.moves import range
|
||
|
|
|
||
|
|
def lcs_length(x, y):
|
||
|
|
"""
|
||
|
|
Computes the length of a Longest Common Subsequence (LCS) of x and y.
|
||
|
|
|
||
|
|
Algorithm adapted from "Introduction to Algorithms" - CLRS.
|
||
|
|
|
||
|
|
@param x: list, one sequence
|
||
|
|
@param y: list, the other sequence
|
||
|
|
|
||
|
|
"""
|
||
|
|
m = len(x)
|
||
|
|
n = len(y)
|
||
|
|
c = dict() # Use dictionary as a 2D array, keys are tuples
|
||
|
|
|
||
|
|
for i in range(m + 1):
|
||
|
|
c[i, 0] = 0
|
||
|
|
|
||
|
|
for j in range(n + 1):
|
||
|
|
c[0, j] = 0
|
||
|
|
|
||
|
|
for i in range(1, m + 1):
|
||
|
|
for j in range(1, n + 1):
|
||
|
|
if x[i - 1] == y[j - 1]:
|
||
|
|
c[i, j] = c[i - 1, j - 1] + 1
|
||
|
|
else:
|
||
|
|
c[i, j] = max(c[i - 1, j], c[i, j - 1])
|
||
|
|
|
||
|
|
return c[m, n]
|