C++题解

ios::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);

以上代码可以加快cin和cout的速度（不用也能AC）。

AC代码↓

#include <iostream>
using namespace std;

bool is_prime(int n);

int main() {
    ios::sync_with_stdio(false);//可省略
    cin.tie(NULL);//可省略
    cout.tie(NULL);//可省略
	string s;
	cin >> s;
	int frequency[26] = {0};
	int m = -1, n = 101;

	for (int i = 0; i < s.size(); ++i) {
		++frequency[s[i] - 'a'];
	}

	for (int i = 0; i < 26; ++i) {
		if (frequency[i] == 0) {
			continue;
		}
		if (frequency[i] > m) {
			m = frequency[i];
		}
		if (frequency[i] < n) {
			n = frequency[i];
		}
	}

	if (is_prime(m - n)) {
		cout << "Lucky Word" << endl;
		cout << m - n << endl;
	} else {
		cout << "No Answer" << endl;
		cout << 0 << endl;
	}

	return 0;
}

bool is_prime(int n) {
	if (n < 2) {
		return false;
	}
	for (int i = 2; i <= n / i; ++i) {
		if (n % i == 0) {
			return false;
		}
	}

	return true;
}

bool is_prime(int n) {
	if (n < 2) {
		return false;
	}
	for (int i = 2; i <= n / i; ++i) {
		if (n % i == 0) {
			return false;
		}
	}

	return true;
}