用二进制的位来表示字母

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
using namespace std;

int main() {
// 注意：在C++中，主函数必须返回一个int类型
int n;
cin >> n;
vector<int> a(n), b(n);
for (int i = 0; i < n; i++) {
string word;
cin >> word;
b[i] = word.length();
for (char c : word) {
a[i] |= 1 << (c - 'a');
}
}
int num = 0;
for (int i = 0; i < a.size(); i++) {
for (int j = i; j < a.size(); j++) {
if ((a[i] & a[j]) == 0) {
num = max(num, b[i] * b[j]);
}
}
}
cout << num << endl;
return 0;
}