#303622 (C++14) No.765 ukuku 2

• 問題: No.765 ukuku 2
• ユーザー: pekempey
• 提出日時: 2018-12-13 02:18:47
• 言語: C++14 (gcc 13.3.0 + boost 1.87.0)
• 結果: AC
• 実行時間: 141 ms / 3,000 ms
• コード長: 1,982 bytes
• コンパイル時間: 362 ms
• コンパイル使用メモリ: 34,944 KB
• 実行使用メモリ: 8,344 KB
• 最終ジャッジ日時: 2024-09-25 04:08:25
• 合計ジャッジ時間: 3,571 ms
• ジャッジサーバーID （参考情報）: judge2 / judge5

ファイルパターン	結果
sample	AC * 2
other	AC * 48

ソースコード

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#define M 1000000007
long long B;
int n;
char s[200001];
char t[200001];
long long H[200001];
long long G[200001];
long long P[200001];
int min(int x, int y) {
    return x < y ? x : y;
}
int max(int x, int y) {
    return x > y ? x : y;
}
long long mod(long long x) {
    x %= M;
    if (x < 0) x += M;
    return x;
}
long long f(int l, int n) {
    return mod(H[l + n] - H[l] * P[n]);
}
long long g(int l, int n) {
    return mod(G[l + n] - G[l] * P[n]);
}
int lcp(int a, int b, int n1, int n2) {
    int l = 0;
    int r = min(n1, n2) + 1;
    while (r - l > 1) {
        int mid = (l + r) / 2;
        if (f(a, mid) == g(b, mid)) {
            l = mid;
        } else {
            r = mid;
        }
    }
    return l;
}
int solve(int a, int b, int n1, int n2) {
    int l = 0;
    int r = min(n1, n2) + 1;
    while (r - l > 1) {
        int mid = (l + r) / 2;
        if (f(a, mid) == g(b, mid)) {
            l = mid;
        } else {
            r = mid;
        }
    }
    a += l;
    b += l;
    n1 -= l;
    n2 -= l;
    int vl = lcp(a, b + 1, n1, n2 - 1);
    int vr = lcp(a + 1, b, n1 - 1, n2);
    return l + max(vl, vr);
}
int main() {
    scanf("%s", s);
    n = strlen(s);
    for (int i = 0; i < n; i++) {
        t[n - 1 - i] = s[i];
    }
    srand(time(NULL));
    B = rand() % M;
    P[0] = 1;
    for (int i = 1; i <= n; i++) {
        P[i] = B * P[i - 1] % M;
    }
    for (int i = 0; i < n; i++) {
        H[i + 1] = (H[i] * B + s[i]) % M;
        G[i + 1] = (G[i] * B + t[i]) % M;
    }
    int ans = 0;
    // odd length
    for (int i = 0; i < n; i++) {
        int x = 2 * solve(i + 1, n - i, n - i - 1, i);
        x = min(x, n - 2);
        ans = max(ans, x + 1);
    }
    // even length
    for (int i = 1; i < n; i++) {
        int x  = 2 * solve(i, n - i, n - i, i);
        x = min(x, n - 1);
        ans = max(ans, x);
    }
    printf("%d\n", ans);
}
 
 
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