#2506 - Count Pairs Of Similar Strings

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Array String Hash Table Bit Manipulation Counting

Problem Description

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.

Solution

/**
 * @param {string[]} words
 * @return {number}
 */
var similarPairs = function(words) {
  const map = new Map();
  let result = 0;

  for (const word of words) {
    const charSet = [...new Set(word.split(''))].sort().join('');
    map.set(charSet, (map.get(charSet) || 0) + 1);
  }

  for (const count of map.values()) {
    if (count > 1) {
      result += (count * (count - 1)) / 2;
    }
  }

  return result;
};