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Submission #1081227

# Submission time Handle Problem Language Result Execution time Memory
1081227 2024-08-29T19:57:32 Z Joshua_Andersson Necklace (Subtask 1-3) (BOI19_necklace1) C++14
45 / 85
 1500 ms 71000 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);
    rep(starta, sz(a))
    {
        repp(startb, 1, sz(b))
        {
            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
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 344 KB Output is correct
2 Correct 12 ms 348 KB Output is correct
3 Correct 9 ms 524 KB Output is correct
4 Correct 9 ms 536 KB Output is correct
5 Correct 12 ms 344 KB Output is correct

Subtask #2
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 344 KB Output is correct
2 Correct 12 ms 348 KB Output is correct
3 Correct 9 ms 524 KB Output is correct
4 Correct 9 ms 536 KB Output is correct
5 Correct 12 ms 344 KB Output is correct
6 Correct 798 ms 1724 KB Output is correct
7 Correct 785 ms 1716 KB Output is correct
8 Correct 591 ms 1372 KB Output is correct
9 Correct 743 ms 1664 KB Output is correct
10 Correct 784 ms 1712 KB Output is correct
11 Correct 779 ms 1696 KB Output is correct
12 Correct 708 ms 1628 KB Output is correct

Subtask #3
0.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 344 KB Output is correct
2 Correct 12 ms 348 KB Output is correct
3 Correct 9 ms 524 KB Output is correct
4 Correct 9 ms 536 KB Output is correct
5 Correct 12 ms 344 KB Output is correct
6 Correct 798 ms 1724 KB Output is correct
7 Correct 785 ms 1716 KB Output is correct
8 Correct 591 ms 1372 KB Output is correct
9 Correct 743 ms 1664 KB Output is correct
10 Correct 784 ms 1712 KB Output is correct
11 Correct 779 ms 1696 KB Output is correct
12 Correct 708 ms 1628 KB Output is correct
13 Execution timed out 1525 ms 71000 KB Time limit exceeded
14 Halted 0 ms 0 KB -