#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);
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);
int l = 10;
auto start = chrono::high_resolution_clock::now();
int rounds = 0;
while (chrono::duration_cast<chrono::milliseconds>(chrono::high_resolution_clock::now() - start).count() < 600)
{
int aa = da(rng);
int ab = aa;
int ba = db(rng);
int bb = ba;
int lo = -1;
int hi = 4000;
while (lo + 1 < hi)
{
int mid = (lo + hi) / 2;
if (aa + mid >= sz(a) || ba + mid >= sz(b) || h1.gethash(aa, aa+mid) != h2.gethash(ba, ba+mid))
{
hi = mid;
}
else lo = mid;
}
aa += hi;
ba += hi;
while (ab > 0 && bb > 0 && a[ab-1] == b[bb-1])
{
ab--;
bb--;
}
int starta = aa;
int startb = bb;
if (rand()%2)
{
starta = ab;
startb = ba;
}
int len = aa - ab;
if (len+1 < l) continue;
rounds++;
int rp = 0;
repp(rlen, 1, min(len+1,l * 2 + 1))
{
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, min(len + 1, l * 2 + 1))
{
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)
{
r = { starta - rp,startb - lp };
if (rev) r.second = sz(b) - r.second - rp - lp;
ret = rp + lp;
l = max(l, ret);
}
}
cerr << "rounds: " << rounds << "\n";
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)
| ^~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1187 ms |
436 KB |
Output is correct |
| 2 |
Partially correct |
1194 ms |
452 KB |
Output is partially correct |
| 3 |
Correct |
1199 ms |
440 KB |
Output is correct |
| 4 |
Partially correct |
1190 ms |
344 KB |
Output is partially correct |
| 5 |
Incorrect |
1195 ms |
440 KB |
Output isn't correct |
| 6 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1187 ms |
436 KB |
Output is correct |
| 2 |
Partially correct |
1194 ms |
452 KB |
Output is partially correct |
| 3 |
Correct |
1199 ms |
440 KB |
Output is correct |
| 4 |
Partially correct |
1190 ms |
344 KB |
Output is partially correct |
| 5 |
Incorrect |
1195 ms |
440 KB |
Output isn't correct |
| 6 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1187 ms |
436 KB |
Output is correct |
| 2 |
Partially correct |
1194 ms |
452 KB |
Output is partially correct |
| 3 |
Correct |
1199 ms |
440 KB |
Output is correct |
| 4 |
Partially correct |
1190 ms |
344 KB |
Output is partially correct |
| 5 |
Incorrect |
1195 ms |
440 KB |
Output isn't correct |
| 6 |
Halted |
0 ms |
0 KB |
- |
