結果

問題 No.599 回文かい
ユーザー uafr_cs
提出日時 2017-11-24 23:36:17
言語 Java
(openjdk 23)
結果
AC  
実行時間 1,763 ms / 4,000 ms
コード長 3,740 bytes
コンパイル時間 2,126 ms
コンパイル使用メモリ 78,728 KB
実行使用メモリ 43,312 KB
最終ジャッジ日時 2024-11-27 08:29:44
合計ジャッジ時間 10,419 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge4
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ファイルパターン 結果
other AC * 22
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

import java.util.Arrays;
import java.util.LinkedList;
import java.util.Scanner;
public class Main {
    
    public static long P1 = 1298719;
    public static long P2 = 961151;
    public static long MOD = 1000000007;
    
    public static long[] rolling_hash1(char[] ins){
        long[] hash = new long[ins.length + 1];
        
        hash[0] = 0;
        for(int i = 1; i <= ins.length; i++){
            hash[i] = hash[i - 1] * P1;
            hash[i] %= MOD;
            hash[i] += ins[i - 1];
            hash[i] %= MOD;
        }
        
        return hash;
    }
    
    public static long[] rolling_hash2(char[] ins){
        long[] hash = new long[ins.length + 1];
        
        hash[0] = 0;
        for(int i = 1; i <= ins.length; i++){
            hash[i] = hash[i - 1] * P2;
            hash[i] %= MOD;
            hash[i] += ins[i - 1];
            hash[i] %= MOD;
        }
        
        return hash;
    }
    
    public static long[] pow1(int len){
        long[] pow = new long[len + 1];
        pow[0] = 1;
        for(int i = 1; i <= len; i++){
            pow[i] = pow[i - 1] * P1;
            pow[i] %= MOD;
        }
        return pow;
    }
    
    public static long[] pow2(int len){
        long[] pow = new long[len + 1];
        pow[0] = 1;
        for(int i = 1; i <= len; i++){
            pow[i] = pow[i - 1] * P2;
            pow[i] %= MOD;
        }
        return pow;
    }
    
    public static long mod_pow(long a, long p){
        if(p == 0){ return 1; }
        if(p == 1){ return a % MOD; }
        if(p % 2 == 1){
            return (mod_pow(a, p - 1) * a) % MOD;
        }else{
            final long ret = mod_pow(a, p / 2) % MOD;
            return (ret * ret) % MOD;
        }
    }
    public static long calc_hash1(long[] hash, int begin, int end, long[] pow1){
        final long from_end = hash[end];
        final long from_begin = (hash[begin] * pow1[end - begin]) % MOD;
        return (MOD + (from_end - from_begin)) % MOD;
    }
    
    public static long calc_hash2(long[] hash, int begin, int end, long[] pow2){
        final long from_end = hash[end];
        final long from_begin = (hash[begin] * pow2[end - begin]) % MOD;
        return (MOD + (from_end - from_begin)) % MOD;
    }
    
    
    public static long dfs(int offset, char[] ins, long[] memo, long[] hash1, long[] hash2, long[] pow1, long[] pow2){
        if(memo[offset] >= 0){ return memo[offset]; }
        
        long ret = 1;
        
        LOOP:
        for(int len = 1; ;len++){
            final int fst_begin = offset;
            final int snd_end = ins.length - offset;
            
            final int snd_begin = snd_end - len;
            final int fst_end = fst_begin + len;
            
            if(fst_end > snd_begin){ break; }
            /*
            System.out.println(fst_begin + " " + snd_begin + " " + len);
            System.out.println("[" + fst_begin + ", " + fst_end + "]");
            //*/
            
            /*
            for(int i = 0; i < len; i++){
                final int fst = fst_begin + i;
                final int snd = snd_begin + i;
                
                if(ins[fst] != ins[snd]){ continue LOOP; }
            }
            //*/
            final long fst_hash1 = calc_hash1(hash1, fst_begin, fst_end, pow1);
            final long snd_hash1 = calc_hash1(hash1, snd_begin, snd_end, pow1);
            
            final long fst_hash2 = calc_hash2(hash2, fst_begin, fst_end, pow2);
            final long snd_hash2 = calc_hash2(hash2, snd_begin, snd_end, pow2);
            
            
            //System.out.println(fst_hash1 + " " + snd_hash1);
            if(fst_hash1 != snd_hash1){ continue; }
            if(fst_hash2 != snd_hash2){ continue; }
                    
            //System.out.println(offset + " " + fst_begin + " " + snd_begin + " " + len);
            ret += dfs(offset + len, ins, memo, hash1, hash2, pow1, pow2);
            ret %= MOD;
        }
        
        return memo[offset] = ret;
    }
    
    public static void main(final String[] args){
        new Thread(null, new Runnable(){
            @Override
            public void run() {
                _main(args);
            }
        }, "", 100 * 1024 * 1024).start();
    }
    
    public static void _main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        final char[] ins = sc.next().toCharArray();
        
        long[] memo = new long[ins.length];
        Arrays.fill(memo, -1);
        
        System.out.println(dfs(0, ins, memo, rolling_hash1(ins), rolling_hash2(ins), pow1(ins.length), pow2(ins.length)));
    }
}
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