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.

class Solution {
public:
    int similarPairs(vector<string>& words) {
        unordered_map<int,int> bits;
        int res = 0;
        for(auto w : words) {
            int now = 0;
            for(auto& ch : w) {
                now |= (1<<(ch-'a'));
            }
            res += bits[now];
            bits[now] += 1;
        }
        return res;
    }
};