String Modification (CodeCraft-20 (Div. 2))

題意説明

Vasya has a string s of length n. He decides to make the following modification to the string: Pick an integer k, (1≤k≤n). For i from 1 to n−k+1, reverse the substring s[i:i+k−1] of s. For example, if string s is qwer and k=2, below is the series of transformations the string goes through: qwer (original string) wqer (after reversing the first substring of length 2) weqr (after reversing the second substring of length 2) werq (after reversing the last substring of length 2) Hence, the resulting string after modifying s with k=2 is werq. Vasya wants to choose a k such that the string obtained after the above-mentioned modification is lexicographically smallest possible among all choices of k. Among all such k, he wants to choose the smallest one. Since he is busy attending Felicity 2020, he asks for your help. A string a is lexicographically smaller than a string b if and only if one of the following holds: a is a prefix of b, but a≠b; in the first position where a and b differ, the string a has a letter that appears earlier in the alphabet than the corresponding letter in b.
Input Each test contains multiple test cases. The first line contains the number of test cases t (1≤t≤5000). The description of the test cases follows. The first line of each test case contains a single integer n (1≤n≤5000) — the length of the string s. The second line of each test case contains the string s of n lowercase latin letters. It is guaranteed that the sum of n over all test cases does not exceed 5000.
Output For each testcase output two lines:
In the first line output the lexicographically smallest string s′ achievable after the above-mentioned modification.
In the second line output the appropriate value of k (1≤k≤n) that you chose for performing the modification. If there are multiple values of k that give the lexicographically smallest string, output the smallest value of k among them.
Example
input 6 4 abab 6 qwerty 5 aaaaa 6 alaska 9 lfpbavjsm 1 p
output abab 1 ertyqw 3 aaaaa 1 aksala 6 avjsmbpfl 5 p 1

構想

まだ1題の選手で、この問題は最初は暴力的なやり方を考えていたが、データの範囲が大きすぎて、法則を探すしかなかったが、長い間探していたが、法則が間違っていることに気づき、奇偶の面から手をつけなかった.この問題の法則は,kから始まる文字列の長さが奇数であれば,k前の文字列を反転させることである.(やはり問題が少なすぎる)

ACコード

#include
#include
#include
#include
#include
#include
#include
#include
#define IOS ios::sync_with_stdio(false); cin.tie(0);
using namespace std;
typedef pair<string,int> PII;
typedef long long ll;
const int N=5050;
const int INF=0x3f3f3f3f;
int main(){
	IOS;
	int T;
	cin>>T;
	while(T--){
		int n;
		string str;
		cin>>n>>str;
		PII t=make_pair(str,1);
		for(int i=2;i<=n;i++){
			string s=str.substr(i-1),u=str.substr(0,i-1);
			if((n-(i+1))%2){
				reverse(u.begin(),u.end());
			}
			t=min(make_pair(s+u,i),t);
		} 
		cout<<t.first<<endl<<t.second<<endl;
	}
	return 0;
}