Submission #658248

#	Time	Username	Problem	Language	Result	Execution time	Memory
658248		600Mihnea	Necklace (Subtask 1-3) (BOI19_necklace1)	C++17	85 / 85	1443 ms	1048 KiB

necklace

bool home = 0;
bool verbose = 1;

#include <bits/stdc++.h>

using namespace std;

mt19937 rng(7777);

typedef long double ld;

const ld PI = 3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808651328230664709384460955058223172535940812848111745028410270193852110555964462294895493038196442881097566593344612847564823378678316527120190914;
using cd = complex<ld>;

ld values[26];

const ld eps = 1e-10;

vector<cd> lol, cs, a;

void place(string s, int len, vector<ld>& sol) {
  int n = (int)s.size();
  if (len > n) {
    return;
  }
  ld ang = 2 * PI / len;
  cd c(cos(ang), sin(ang));
  cs.resize(len);
  a.resize(n);
 	sol.clear();
 	sol.resize(n - len + 1, 0);
  cs[0] = 1;
  for (int i = 1; i < len; i++) {
    cs[i] = cs[i - 1] * c;
  }
  for (int i = 0; i < n; i++) {
    a[i] = values[s[i] - 'a'];
  } 
  vector<cd> vl(n, 0);
 	for (int i = 0; i + len - 1 < n; i++) {
 		if (i >= 1) {
 			vl[i] = vl[i - 1];
 			vl[i] -= a[i - 1];
 			vl[i] /= c;
 			vl[i] += cs[len - 1] * a[i + len - 1];
 		} else {
	 		for (int j = 0; j < len; j++) {
	 			vl[i] += cs[j] * a[i + j];
			}
		}
 	}
 	for (int i = 0; i + len - 1 < n; i++) {
 		sol[i] = norm(vl[i]);
 	}
}

string s, t;
vector<ld> norms_s, norms_t;

bool isok(int len) {
  place(s, len, norms_s);
  place(t, len, norms_t);
  int n = (int)norms_s.size();
  int m = (int)norms_t.size();
  sort(norms_s.begin(), norms_s.end());
  sort(norms_t.begin(), norms_t.end());
  int j = 0;
  for (int i = 0; i < n; i++) {
    while (j < m && norms_t[j] < norms_s[i]) {
      j++;
    }
    if (0 <= j && j < m && abs(norms_s[i] - norms_t[j]) < eps) {
      return 1;
    }
    if (0 <= j - 1 && j - 1 < m && abs(norms_s[i] - norms_t[j - 1]) < eps) {
      return 1;
    }
  }
  return 0;
}

void print(int len) {
  place(s, len, norms_s);
  place(t, len, norms_t);
  int n = (int)norms_s.size();
  int m = (int)norms_t.size();
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (abs(norms_s[i] - norms_t[j]) < eps) {
        cout << i << " " << j << "\n";
        exit(0);
      }
    }
  }
}

int main() {
  for (int x = 0; x < 26; x++) {
    values[x] = cos(rng());
  }
  if (!home) {
    verbose = 0;
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
  }
  if (home) {
    verbose = 1;
    freopen("___input___.txt", "r", stdin);
  }

  cin >> s >> t;
  int n = (int)s.size(), m = (int)t.size();
  int len = min(n, m);
  while (!isok(len)) {
    if (verbose) {
      cout << "len = " << len << "\n";
    }
    len--;
  }
  cout << len << "\n";
  print(len);
  return 0;
}

Compilation message (stderr)

necklace.cpp: In function 'int main()':
necklace.cpp:109:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  109 |     freopen("___input___.txt", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 25 / 25
• Subtask 2: 20 / 20
• Subtask 3: 40 / 40