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Common Child.py
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Common Child.py
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"""
Given two strings a and b of equal length, what's the longest string (S) that can be constructed such that S is a child
of both a and b.
A string x is said to be a child of a string y, if x can be formed by deleting 0 or more characters from y
Input format
Two strings a and b with a newline separating them
"""
__author__ = 'Danyang'
class Solution(object):
def solve_error(self, cipher):
"""
dp
error transition:
dp[i][j] = dp[i-1][j] + 1 if a[i]==b[j]
dp[i][j] = max(dp[i][j-1], dp[i-1][j]) if a[i]!=b[j]
:param cipher: the cipher
"""
a, b = cipher
m = len(a)
n = len(b)
dp = [[0 for _ in xrange(n + 1)] for _ in xrange(m + 1)]
for i in xrange(1, m + 1):
for j in xrange(1, n + 1):
if a[i - 1] == b[j - 1]:
dp[i][j] = min(dp[i][j - 1], dp[i - 1][j]) + 1
else:
dp[i][j] = max(dp[i][j - 1], dp[i - 1][j]) # superset
return dp[-1][-1]
def solve(self, cipher):
"""
dp
dp longest common sequence
dp[i][j] = dp[i-1][j-1] + 1 if a[i]==b[j]
dp[i][j] = max(dp[i][j-1], dp[i-1][j]) if a[i]!=b[j]
:param cipher: the cipher
"""
a, b = cipher
m = len(a)
n = len(b)
dp = [[0 for _ in xrange(n + 1)] for _ in xrange(m + 1)]
for i in xrange(1, m + 1):
for j in xrange(1, n + 1):
if a[i - 1] == b[j - 1]:
dp[i][j] = dp[i - 1][j - 1] + 1
else:
dp[i][j] = max(dp[i][j - 1], dp[i - 1][j]) # superset
return dp[-1][-1]
if __name__ == "__main__":
import sys
f = open("1.in", "r")
# f = sys.stdin
cipher = []
cipher.append(f.readline().strip())
cipher.append(f.readline().strip())
s = "%s\n" % (Solution().solve(cipher))
print s,