Short Problem Definition:
Given two strings a and b of equal length, what’s the longest string (S) that can be constructed such that it is a child of both?
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.
Link
Complexity:
time complexity is O(N*M)
space complexity is O(N*M)
Execution:
This is a longest common subsequence problem in disguise. I encourage you to look at a good explanation here.
Solution:
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#!/usr/bin/pydef lcs(a, b):lengths = [[0 for j in range(len(b)+1)] for i in range(len(a)+1)]for i, x in enumerate(a):for j, y in enumerate(b):if x == y:lengths[i+1][j+1] = lengths[i][j] + 1else:lengths[i+1][j+1] = max(lengths[i+1][j], lengths[i][j+1])return lengths[-1][-1]def main():s1 = raw_input()s2 = raw_input()print lcs(s1,s2)if __name__ == '__main__':main() |
