#1004477 (C++17) No.2858 Make a Palindrome

• 問題: No.2858 Make a Palindrome
• ユーザー: 沙耶花
• 提出日時: 2024-08-25 14:20:03
• 言語: C++17 (gcc 12.3.0 + boost 1.83.0)
• 結果: AC
• 実行時間: 448 ms / 3,000 ms
• コード長: 3,164 bytes
• コンパイル時間: 4,735 ms
• コンパイル使用メモリ: 268,364 KB
• 実行使用メモリ: 34,964 KB
• 最終ジャッジ日時: 2024-08-25 14:20:15
• 合計ジャッジ時間: 10,462 ms
• ジャッジサーバーID （参考情報）: judge5 / judge3

入力	結果	実行時間; 実行使用メモリ
testcase_00	AC	448 ms; 6,816 KB
testcase_01	AC	94 ms; 6,940 KB
testcase_02	AC	96 ms; 6,940 KB
testcase_03	AC	94 ms; 6,940 KB
testcase_04	AC	97 ms; 6,940 KB
testcase_05	AC	78 ms; 6,940 KB
testcase_06	AC	74 ms; 6,944 KB
testcase_07	AC	72 ms; 6,940 KB
testcase_08	AC	71 ms; 6,940 KB
testcase_09	AC	71 ms; 6,940 KB
testcase_10	AC	74 ms; 6,944 KB
testcase_11	AC	71 ms; 6,940 KB
testcase_12	AC	72 ms; 6,940 KB
testcase_13	AC	73 ms; 6,940 KB
testcase_14	AC	74 ms; 6,940 KB
testcase_15	AC	66 ms; 6,940 KB
testcase_16	AC	66 ms; 6,944 KB
testcase_17	AC	67 ms; 6,944 KB
testcase_18	AC	68 ms; 6,940 KB
testcase_19	AC	66 ms; 6,940 KB
testcase_20	AC	115 ms; 30,872 KB
testcase_21	AC	108 ms; 31,488 KB
testcase_22	AC	55 ms; 17,664 KB
testcase_23	AC	104 ms; 28,456 KB
testcase_24	AC	93 ms; 28,516 KB
testcase_25	AC	78 ms; 24,888 KB
testcase_26	AC	70 ms; 21,212 KB
testcase_27	AC	122 ms; 34,544 KB
testcase_28	AC	94 ms; 28,060 KB
testcase_29	AC	99 ms; 29,520 KB
testcase_30	AC	123 ms; 34,072 KB
testcase_31	AC	110 ms; 34,200 KB
testcase_32	AC	116 ms; 34,328 KB
testcase_33	AC	114 ms; 34,076 KB
testcase_34	AC	110 ms; 33,812 KB
testcase_35	AC	113 ms; 34,964 KB
testcase_36	AC	116 ms; 34,588 KB
testcase_37	AC	115 ms; 34,716 KB
testcase_38	AC	114 ms; 34,328 KB
testcase_39	AC	112 ms; 34,712 KB

ソースコード

#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 1000000000000000001

struct rolling_hash{

	long long t_hash;
	static inline vector<long long> power;
	static const long long MOD = (1LL<<61)-1;
	static const long long b = 123456;
	int sz;
	
	rolling_hash(){		
		sz = 0;
		t_hash = 0;
	}
	
	rolling_hash(char c){
		sz = 1;
		t_hash = b*c;
	}

	long long mul(__int128 x,__int128 y){
		__int128 t = x*y;
		t = (t>>61) + (t&MOD);
		
		if(t>=MOD)t -= MOD;
		return t;
	}
	
	long long get_pow(int sz){
		if(power.size()>sz)return power[sz];
		
		while(power.size()<=sz){
			if(power.size()==0)power.push_back(1);
			else power.push_back(mul(power.back(),b));
		}
		return power.back();
		
	}
	
	rolling_hash &operator+=(const rolling_hash &another){
		
		(*this).t_hash = mul((*this).t_hash,get_pow(another.sz));
		(*this).t_hash += another.t_hash;
		if((*this).t_hash>=MOD)(*this).t_hash -= MOD;
			
		(*this).sz += another.sz;
		
		return (*this);
	}
	
	rolling_hash operator+(const rolling_hash &another)const{
		return (rolling_hash(*this)+=another);
	}
	
	rolling_hash &operator-=(const rolling_hash &another){

		(*this).t_hash += MOD - mul(another.t_hash,get_pow((*this).sz-another.sz));
		if((*this).t_hash>=MOD)(*this).t_hash -= MOD;
			
		(*this).sz -= another.sz;

		return (*this);
	}
	
	rolling_hash operator-(const rolling_hash &another)const{
		return (rolling_hash(*this)-=another);
	}
	
	bool operator<(const rolling_hash &another)const{
		if((*this).t_hash!=another.t_hash)return (*this).t_hash<another.t_hash;
		return (*this).sz<another.sz;
	}
	
	bool operator==(const rolling_hash &another)const{
		return ((*this).t_hash==another.t_hash && (*this).sz==another.sz);
	}

	
};
void solve(){
	long long n,m;
	cin>>n>>m;
	string S;
	cin>>S;
	S = S+S+S+S;
	vector<rolling_hash> h(n*4+1), rh(n*4+1);
	//cout<<'a'<<endl;
	rep(i,n*4){
		h[i+1] = h[i]+rolling_hash(S[i]);
		rh[i+1] = rh[i]+rolling_hash(S[n*4-i-1]);
	}
	//cout<<'b'<<endl;
	long long ans = Inf64;
	rep(i,n){
		int ok = 0,ng = n+1;
		while(ng-ok>1){
			int mid = (ok+ng)/2;
			int l = n+i;
			int r = l+1;
			l -= mid,r += mid;
			if(h[r]-h[l]==rh[n*4-l]-rh[n*4-r])ok = mid;
			else ng = mid;
		}
		if(ok==n||ok*2+1 >= m){
			long long mm = m;
			if(mm%2==0)mm++;
			long long l = i - mm/2;
			long long r = l + mm;
			if(l<0){
				long long D  =-l;
				D = (D+n-1)/n;
				l += D*n, r+=D*n;
			}
			ans = min((r+n-1)/n, ans);
		}
	}
	rep(i,n){
		if(S[i]!=S[i+1])continue;
		int ok = 0,ng = n+1;
		while(ng-ok>1){
			int mid = (ok+ng)/2;
			int l = n+i;
			int r = l+2;
			l -= mid,r += mid;
			if(h[r]-h[l]==rh[n*4-l]-rh[n*4-r])ok = mid;
			else ng = mid;
		}
		if(ok==n||ok*2+2 >= m){
			long long mm = m;
			if(mm%2==1)mm++;
			long long l = i - (mm-2)/2;
			long long r = l + mm;
			if(l<0){
				long long D  =-l;
				D = (D+n-1)/n;
				l += D*n, r+=D*n;
			}
			ans = min((r+n-1)/n, ans);
		}
	}
	if(ans==Inf64)ans = -1;
	cout<<ans<<endl;
}
int main(){
	int _t;
	cin>>_t;
	rep(_,_t)solve();
	
    return 0;
}