A. Reverse and Concatenate

如果k为0直接输出1，否则如果s为回文串的话输出1，其他情况输出2（经过一次变换后必然为回文）。注意不能特判k = 1的情况，用这个样例hack了一发23333

#include <bits/stdc++.h>
#define pii pair<int,int>
#define pb push_back
using namespace std;
int n, k;
void solve() {
	cin >> n >> k;
	string s;
	cin >> s;
	if(k == 0) {
		cout << 1 << endl;
		return;
	} else {
		string ss = s;
		reverse(ss.begin(), ss.end());
		if(ss == s) cout << 1 << endl;
		else cout << 2 << endl;
		return;
	}
}
int main() {
	int T = 1;
	cin >> T;
	while(T--) {
		solve();
	}
	return 0;
}
// 1
// 2 1
// ab

B. Fortune Telling

Your friends Alice and Bob practice fortune telling.

Fortune telling is performed as follows. There is a well-known array

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来源： https://www.cnblogs.com/lipoicyclic/p/15866776.html