cpp
class Solution {
public:
    int maxProduct(vector<string>& words) {

          int n = words.size();
          vector<int> masks(n);

          for(int i=0; i<n; i++) {
            int mask = 0;
            for(char c: words[i]) {
              mask |= 1<<(c-'a'); 
            }
            masks[i] = mask; 
          }

          int ans = 0;

          for(int i=0; i<n; i++) {
            for(int j=i+1; j<n; j++) {
              if((masks[i]&masks[j])==0) {
                ans = max(ans, int(words[i].size()*words[j].size()));
              }
            }
          }

          return ans;
    }
};