Syntax error Program to find number of subsequence that are present inside word list in python

Program to find number of subsequence that are present inside word list in python

Suppose we have a list of words and a string s, we have to find the number of strings in the words list that are subsequences of s.

So, if the input is like words = ["xz", "xw", "y"] s = "xyz", then the output will be 2, as "xz" and "y" are subsequences of "xyz".

To solve this, we will follow these steps −

  • ans := 0
  • d := an empty map
  • for each word in words, do
    • insert word at the end of d[word[0]]
  • for each c in s, do
    • l := d[c]
    • d[c] := a new list
    • for each word in l, do
      • if size of word is 1, then
        • ans := ans + 1
      • otherwise,
        • insert substring of word[from index 1 to end] at the end of d[word[1]]
  • return ans

Let us see the following implementation to get better understanding −

Example 

Live Demo

from collections import defaultdict
class Solution:
   def solve(self, words, s):
      ans = 0

      d = defaultdict(list)
      for word in words:
         d[word[0]].append(word)

      for c in s:
         l = d[c]
         d[c] = []

         for word in l:
            if len(word) == 1:
               ans += 1
            else:
               d[word[1]].append(word[1:])
      return ans
ob = Solution()
words = ["xz", "xw", "y"]
s = "xyz"
print(ob.solve(words, s))

Input

["xz", "xw", "y"], "xyz"

Output

2
Updated on: 2020-12-02T05:07:01+05:30

398 Views

Kickstart Your Career

Get certified by completing the course

Get Started
Advertisements