README.md

2506. Count Pairs Of Similar Strings

You are given a 0-indexed string array words.

Two strings are similar if they consist of the same characters.

• For example, "abca" and "cba" are similar since both consist of characters 'a', 'b', and 'c'.
• However, "abacba" and "bcfd" are not similar since they do not consist of the same characters.

Return the number of pairs (i, j) such that 0 <= i < j <= word.length - 1 and the two strings words[i] and words[j] are similar.

Example 1:

Input: words = ["aba","aabb","abcd","bac","aabc"]
Output: 2
Explanation: There are 2 pairs that satisfy the conditions:
- i = 0 and j = 1 : both words[0] and words[1] only consist of characters 'a' and 'b'.
- i = 3 and j = 4 : both words[3] and words[4] only consist of characters 'a', 'b', and 'c'.

Example 2:

Input: words = ["aabb","ab","ba"]
Output: 3
Explanation: There are 3 pairs that satisfy the conditions:
- i = 0 and j = 1 : both words[0] and words[1] only consist of characters 'a' and 'b'.
- i = 0 and j = 2 : both words[0] and words[2] only consist of characters 'a' and 'b'.
- i = 1 and j = 2 : both words[1] and words[2] only consist of characters 'a' and 'b'.

Example 3:

Input: words = ["nba","cba","dba"]
Output: 0
Explanation: Since there does not exist any pair that satisfies the conditions, we return 0.

Constraints:

• 1 <= words.length <= 100
• 1 <= words[i].length <= 100
• words[i] consist of only lowercase English letters.

Solutions (Rust)

1. Solution

use std::collections::HashMap;

impl Solution {
    pub fn similar_pairs(words: Vec<String>) -> i32 {
        let mut count = HashMap::new();

        for word in &words {
            let x = word.bytes().fold(0, |acc, b| acc | (1 << (b - b'a')));

            count.entry(x).and_modify(|c| *c += 1).or_insert(1);
        }

        count.values().map(|c| c * (c - 1) / 2).sum()
    }
}