Skip to content

Create longestCommonSubsequence.py #497

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
HarshaK1302 wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Create longestCommonSubsequence.py #497

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
43 changes: 43 additions & 0 deletions longestCommonSubsequence.py
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,43 @@

def lcs(u, v):

c = [[-1]*(len(v) + 1) for _ in range(len(u) + 1)]
lcs_helper(u, v, c, 0, 0)
return c


def lcs_helper(u, v, c, i, j):

if c[i][j] >= 0:
return c[i][j]

if i == len(u) or j == len(v):
q = 0
else:
if u[i] == v[j]:
q = 1 + lcs_helper(u, v, c, i + 1, j + 1)
else:
q = max(lcs_helper(u, v, c, i + 1, j),
lcs_helper(u, v, c, i, j + 1))
c[i][j] = q
return q


def print_lcs(u, v, c):
i = j = 0
while not (i == len(u) or j == len(v)):
if u[i] == v[j]:
print(u[i], end='')
i += 1
j += 1
elif c[i][j + 1] > c[i + 1][j]:
j += 1
else:
i += 1


u = input('Enter first string: ')
v = input('Enter second string: ')
c = lcs(u, v)
print('Longest Common Subsequence: ', end='')
print_lcs(u, v, c)