You are given an array of strings ideas
that represents a list of names to be used in the process of naming a company. The process of naming a company is as follows:
- Choose 2 distinct names from
ideas
, call themideaA
andideaB
. - Swap the first letters of
ideaA
andideaB
with each other. - If both of the new names are not found in the original
ideas
, then the nameideaA ideaB
(the concatenation ofideaA
andideaB
, separated by a space) is a valid company name. - Otherwise, it is not a valid name.
Return the number of distinct valid names for the company.
Example 1:
Input: ideas = ["coffee","donuts","time","toffee"]
Output: 6
Explanation: The following selections are valid:
- ("coffee", "donuts"): The company name created is "doffee conuts".
- ("donuts", "coffee"): The company name created is "conuts doffee".
- ("donuts", "time"): The company name created is "tonuts dime".
- ("donuts", "toffee"): The company name created is "tonuts doffee".
- ("time", "donuts"): The company name created is "dime tonuts".
- ("toffee", "donuts"): The company name created is "doffee tonuts". Therefore, there are a total of 6 distinct company names.
The following are some examples of invalid selections:
- ("coffee", "time"): The name "toffee" formed after swapping already exists in the original array.
- ("time", "toffee"): Both names are still the same after swapping and exist in the original array.
- ("coffee", "toffee"): Both names formed after swapping already exist in the original array.
Example 2:
Input: ideas = ["lack","back"]
Output: 0
Explanation: There are no valid selections. Therefore, 0 is returned.
Constraints:
-
2 <= ideas.length <= 5 * 104
-
1 <= ideas[i].length <= 10
-
ideas[i]
consists of lowercase English letters. - All the strings in
ideas
are unique.
SOLUTION:
from collections import Counter
class Solution:
def distinctNames(self, ideas: List[str]) -> int:
names = set(ideas)
groups = [[] for _ in range(26)]
groupctr = Counter()
for idea in ideas:
groups[ord(idea[0]) - ord('a')].append(idea)
for l in 'abcdefghijklmnopqrstuvwxyz':
for c in 'abcdefghijklmnopqrstuvwxyz':
for pair in groups[ord(l) - ord('a')]:
if (c + pair[1:]) not in names:
groupctr[(l, c)] += 1
ctr = 0
for idea in ideas:
for c in 'abcdefghijklmnopqrstuvwxyz':
if (c + idea[1:]) not in names:
ctr += groupctr[(c, idea[0])]
return ctr
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