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Submission #1081237

# Submission time Handle Problem Language Result Execution time Memory
1081237 2024-08-29T20:03:52 Z Joshua_Andersson Necklace (Subtask 1-3) (BOI19_necklace1) C++14
9 / 85
 1500 ms 70992 KB 
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
#define int ll
const int inf = int(1e18);

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int, int> p2;

#define rep(i, high) for (int i = 0; i < high; i++)
#define repp(i, low, high) for (int i = low; i < high; i++)
#define repe(i, container) for (auto& i : container)
#define sz(container) ((int)container.size())
#define all(x) begin(x),end(x)

inline void fast() { ios::sync_with_stdio(0); cin.tie(0); cout.tie(0); }

#if _LOCAL
#define assert(x) if (!(x)) __debugbreak()
#endif

typedef unsigned long long ull;

struct RollingHash
{
    vector<ull> suf, b;
    int mod;
    RollingHash(string& s, ull base = 131, ull mod = 1e9 + 7) : mod(mod), suf(s.size() + 1), b(s.size() + 1)
    {
        b[0] = 1;
        b[1] = base;

        for (int i = sz(s) - 1; i >= 0; i--)
        {
            suf[i] = (suf[i + 1] * base + s[i]) % mod;
        }

        repp(i, 2, s.size() + 1)
        {
            b[i] = b[i - 1] * b[1] % mod;
        }
    }

    ull gethash(int l, int r) // hash s[l, r]
    {
        ull rv = (suf[r + 1] * b[r - l + 1]) % mod;
        return suf[l] + mod * (suf[l] < rv) - rv;
    }
};

struct DoubleHash
{
    RollingHash h1;
    RollingHash h2;
    DoubleHash(string& s, ull mod = 1e9 + 7) : h1(s, 157, mod), h2(s, 131, mod) {}
    ull gethash(int l, int r)
    {
        return (h1.gethash(l, r) << 32) + h2.gethash(l, r);
    }
};

pair<int,p2> best(string a, string b, bool rev)
{
    int ret = -1;
    p2 r = p2(-1, -1);
    vvi lcp(sz(a), vi(sz(b)));
    DoubleHash h1(a);
    DoubleHash h2(b);
    mt19937 rng;
    uniform_int_distribution<int> da(0, sz(a) - 1);
    uniform_int_distribution<int> db(0, sz(b) - 1);

    rep(i, sz(a) * sz(b))
    {
        int starta = da(rng);
        int startb = db(rng);
        int rp = 0;
        repp(rlen, 1, 1000)
        {
            int i = starta - rlen;
            int j = startb;
            if (i < 0 || j + rlen - 1 >= sz(b)) break;
            bool good = h1.gethash(i, i + rlen - 1) == h2.gethash(j, j + rlen - 1);
            if (good) rp = rlen;
        }
        int lp = 0;
        repp(llen, 1, 1000)
        {
            int i = starta;
            int j = startb - llen;
            if (j < 0 || i + llen - 1 >= sz(a)) break;
            bool good = h1.gethash(i, i + llen - 1) == h2.gethash(j, j + llen - 1);
            if (good) lp = llen;
        }

        if (rp + lp > ret)
        {
            //assert(rp + lp != 84);
            r = { starta - rp,startb - lp };
            if (rev) r.second = sz(b) - r.second - rp - lp;
            ret = rp + lp;
        }
    }
    return { ret, r };
}

signed main()
{
    fast();

    string a, b;
    cin >> a >> b;
    pair<int, p2> ans = { -1000,p2(0,0) };
    ans = max(ans, best(a, b, 0));
    reverse(all(b));
    ans = max(ans, best(a, b, 1));
    cout << ans.first << "\n" << ans.second.first << " " << ans.second.second;

    return 0;
}

Compilation message

necklace.cpp: In constructor 'RollingHash::RollingHash(std::string&, ull, ull)':
necklace.cpp:29:9: warning: 'RollingHash::mod' will be initialized after [-Wreorder]
   29 |     int mod;
      |         ^~~
necklace.cpp:28:17: warning:   'std::vector<long long unsigned int> RollingHash::suf' [-Wreorder]
   28 |     vector<ull> suf, b;
      |                 ^~~
necklace.cpp:30:5: warning:   when initialized here [-Wreorder]
   30 |     RollingHash(string& s, ull base = 131, ull mod = 1e9 + 7) : mod(mod), suf(s.size() + 1), b(s.size() + 1)
      |     ^~~~~~~~~~~
necklace.cpp:13:48: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   13 | #define repp(i, low, high) for (int i = low; i < high; i++)
......
   40 |         repp(i, 2, s.size() + 1)
      |              ~~~~~~~~~~~~~~~~~~                 
necklace.cpp:40:9: note: in expansion of macro 'repp'
   40 |         repp(i, 2, s.size() + 1)
      |         ^~~~

Subtask #1
5.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 348 KB Output is correct
2 Partially correct 13 ms 544 KB Output is partially correct
3 Correct 9 ms 348 KB Output is correct
4 Correct 10 ms 532 KB Output is correct
5 Correct 13 ms 348 KB Output is correct

Subtask #2
4.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 348 KB Output is correct
2 Partially correct 13 ms 544 KB Output is partially correct
3 Correct 9 ms 348 KB Output is correct
4 Correct 10 ms 532 KB Output is correct
5 Correct 13 ms 348 KB Output is correct
6 Correct 798 ms 1628 KB Output is correct
7 Partially correct 793 ms 1624 KB Output is partially correct
8 Correct 604 ms 1512 KB Output is correct
9 Correct 743 ms 1664 KB Output is correct
10 Partially correct 784 ms 1624 KB Output is partially correct
11 Correct 784 ms 1628 KB Output is correct
12 Partially correct 720 ms 1624 KB Output is partially correct

Subtask #3
0.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 348 KB Output is correct
2 Partially correct 13 ms 544 KB Output is partially correct
3 Correct 9 ms 348 KB Output is correct
4 Correct 10 ms 532 KB Output is correct
5 Correct 13 ms 348 KB Output is correct
6 Correct 798 ms 1628 KB Output is correct
7 Partially correct 793 ms 1624 KB Output is partially correct
8 Correct 604 ms 1512 KB Output is correct
9 Correct 743 ms 1664 KB Output is correct
10 Partially correct 784 ms 1624 KB Output is partially correct
11 Correct 784 ms 1628 KB Output is correct
12 Partially correct 720 ms 1624 KB Output is partially correct
13 Execution timed out 1520 ms 70992 KB Time limit exceeded
14 Halted 0 ms 0 KB -