結果

問題 No.599 回文かい
ユーザー pop_o
提出日時 2024-09-22 15:57:44
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 112 ms / 4,000 ms
コード長 2,764 bytes
コンパイル時間 2,034 ms
コンパイル使用メモリ 200,712 KB
最終ジャッジ日時 2025-02-24 11:32:17
ジャッジサーバーID
（参考情報） 		judge5 / judge1
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ファイルパターン 結果
other AC * 22
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ソースコード

diff #
プレゼンテーションモードにする

#include<bits/stdc++.h>
using namespace std;
const long long mod = 1000000007;
#define dmp(x) cerr << "line " << __LINE__ << " " << #x << " : " << x << "\n"
const uint64_t hashmod = 0x1fffffffffffffff;
const uint64_t base = chrono::duration_cast<chrono::microseconds>(chrono::system_clock::now().time_since_epoch()).count() % hashmod;
const uint64_t mdf = uint64_t(1e17) + 1;
template<typename T>
struct rolling_hash {
    int n;
    vector<uint64_t> hash, p;
    
    inline uint64_t mul(uint64_t a, uint64_t b) const {
        uint64_t a31 = a >> 31, b31 = b >> 31;
        a &= 0x7fffffffull; b &= 0x7fffffffull;
        uint64_t x = a * b31 + b * a31;
        uint64_t res = (a31 * b31 << 1) + (x >> 30) + ((x & 0x3fffffffull) << 31) + a * b;
        res = (res >> 61) + (res & hashmod);
        if (res >= hashmod) res -= hashmod;
        return res;
    }
    
    rolling_hash(const T &a) {
        n = (int)a.size();
        hash.assign(n + 1, 0ull);
        p.assign(n + 1, 0ull);
        p[0] = 1;
        for(int i = 0; i < n; i++) {
            p[i + 1] = mul(p[i], base);
            hash[i + 1] = mul(hash[i], base) + (mdf + (uint64_t)a[i]);
            if(hash[i + 1] >= hashmod) hash[i + 1] -= hashmod;
        }
    }
    
    // get hashing of S[l, r)
    inline uint64_t get(int l, int r) const {
        uint64_t res = hash[r] + hashmod - mul(hash[l], p[r - l]);
        if (res >= hashmod) res -= hashmod;
        return res;
    }
    
    // return longest common prefixes of a and b
    inline int lcp(const rolling_hash &b, int l1, int r1, int l2, int r2) const {
        int size = min(r1 - l1, r2 - l2);
        int ok = 0, ng = size + 1;
        while(ng - ok > 1) {
            int mid = (ok + ng) / 2;
            if(get(l1, l1 + mid) == b.get(l2, l2 + mid)) ok = mid;
            else ng = mid;
        }
        return ok;
    }
    
    // return hash1 + hash2 
    inline uint64_t connect(uint64_t hash1, uint64_t hash2, int hash2size) const {
        uint64_t res = mul(hash1, p[hash2size]) + hash2;
        if (res >= hashmod) res -= hashmod;
        return res;
    }
};
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    string s;
    cin >> s;
    int n = (int) s.size();
    if (n % 2 == 0) {
        s = s.substr(0, n/2) + '~' + s.substr(n/2);
        n++;
    }
    rolling_hash h(s);
    vector<long long> dp(n+1, 0);
    dp[0] = 1;
    for (int i = 0; i <= n/2; i++) {
        for (int j = i+1; j <= n/2; j++) {
            if (h.get(i, j) == h.get(n-j, n-i)) {
                dp[j] += dp[i];
                dp[j] %= mod;
            }
        }
    }
    long long ans = 0;
    for (int i = 1; i <= n/2; i++) {
        ans += dp[i];
        ans %= mod;
    }
    cout << ++ans%mod << "\n";
}
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