Naming a company

Array Hash Table String Bit Manipulation Enumeration

46.5% acceptance

Feb 25, 2026

1966

You are given an array of strings ideas that represents a list of names to be used in naming a company. The process of naming a company: Choose 2 distinct names, ideaA and ideaB. Swap the first letters. If both new names are not found in the original ideas, then "ideaA ideaB" is a valid company name. Return the number of distinct valid names for the company.

Solution

Rust

Time O(n²)

Space O(n)

LeetCode

solution.rs

use std::collections::HashSet;


impl Solution {
  pub fn distinct_names(ideas: Vec<String>) -> i64 {
    let mut suffix_sets: Vec<HashSet<String>> = vec![HashSet::new(); 26];
    for idea in &ideas {
      let idx = (idea.as_bytes()[0] - b'a') as usize;
      suffix_sets[idx].insert(idea[1..].to_string());
    }
    let mut ans: i64 = 0;
    for a in 0..26usize {
      for b in (a + 1)..26usize {
        let common = suffix_sets[a].intersection(&suffix_sets[b]).count() as i64;
        let a_only = suffix_sets[a].len() as i64 - common;
        let b_only = suffix_sets[b].len() as i64 - common;
        ans += 2 * a_only * b_only;
      }
    }
    ans
  }
}