- Difficulty: Medium
- Tags: LeetCode, Medium, Bit Manipulation, Array, Hash Table, String, Sorting, leetcode-2135, O(n), Bitmasks
Problem
You are given two 0-indexed arrays of strings startWords
and targetWords
. Each string consists of lowercase English letters only.
For each string in targetWords
, check if it is possible to choose a string from startWords
and perform a conversion operation on it to be equal to that from targetWords
.
The conversion operation is described in the following two steps:
- Append any lowercase letter that is not present in the string to its end.
- For example, if the string is
"abc"
, the letters'd'
,'e'
, or'y'
can be added to it, but not'a'
. If'd'
is added, the resulting string will be"abcd"
.
- For example, if the string is
- Rearrange the letters of the new string in any arbitrary order.
- For example,
"abcd"
can be rearranged to"acbd"
,"bacd"
,"cbda"
, and so on. Note that it can also be rearranged to"abcd"
itself.
- For example,
Return the number of strings in targetWords
that can be obtained by performing the operations on any string of startWords
.
Note that you will only be verifying if the string in targetWords
can be obtained from a string in startWords
by performing the operations. The strings in startWords
do not actually change during this process.
Example 1:
Input: startWords = ["ant","act","tack"], targetWords = ["tack","act","acti"] Output: 2 Explanation: - In order to form targetWords[0] = "tack", we use startWords[1] = "act", append 'k' to it, and rearrange "actk" to "tack". - There is no string in startWords that can be used to obtain targetWords[1] = "act". Note that "act" does exist in startWords, but we must append one letter to the string before rearranging it. - In order to form targetWords[2] = "acti", we use startWords[1] = "act", append 'i' to it, and rearrange "acti" to "acti" itself.
Example 2:
Input: startWords = ["ab","a"], targetWords = ["abc","abcd"] Output: 1 Explanation: - In order to form targetWords[0] = "abc", we use startWords[0] = "ab", add 'c' to it, and rearrange it to "abc". - There is no string in startWords that can be used to obtain targetWords[1] = "abcd".
Constraints:
1 <= startWords.length, targetWords.length <= 5 * 104
1 <= startWords[i].length, targetWords[j].length <= 26
- Each string of
startWords
andtargetWords
consists of lowercase English letters only. - No letter occurs more than once in any string of
startWords
ortargetWords
.