제출 #658233

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
658233		600Mihnea	Necklace (Subtask 1-3) (BOI19_necklace1)	C++17	45 / 85	1588 ms	807876 KiB

necklace

bool home = 0;
bool verbose = 1;
 
#include <bits/stdc++.h>
 
using namespace std;
 
mt19937 rng(7777);
 
typedef double ld;
 
const ld PI = 3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808651328230664709384460955058223172535940812848111745028410270193852110555964462294895493038196442881097566593344612847564823378678316527120190914;
using cd = complex<ld>;
 
int getlog2(int x) {
  if (x == 1) return 0;
  return 1 + getlog2(x / 2);
}
 
void fft(vector<cd>& a, bool inv) {
  int n = (int)a.size(), k = getlog2(n);
 
  for (int i = 0; i < n; i++) {
    int j = 0;
    for (int bit = 0; bit < k; bit++) {
      if (i & (1 << bit)) {
        j += (1 << (k - 1 - bit));
      }
    }
    if (i < j) {
      swap(a[i], a[j]);
    }
  }
 
  for (int l = 2; l <= n; l *= 2) {
    ld ang = 2 * PI / (ld)l;
    if (inv) ang *= -1;
    cd mlt(cos(ang), sin(ang));
    for (int i = 0; i < n; i += l) {
      cd cur(1);
      for (int j = 0; j < l / 2; j++) {
        cd x = a[i + j];
        cd y = a[i + l / 2 + j] * cur;
        a[i + j] = x + y;
        a[i + l / 2 + j] = x - y;
        cur *= mlt;
      }
    }
  }
 
  if (inv) {
    for (auto& x : a) {
      x /= n;
    }
  }
}
 
void conv_smart(vector<cd> a, vector<cd> b, vector<cd> &sol) {
  int n = 1;
  while (n <= (int)a.size() + (int)b.size()) n *= 2;
 
  a.resize(n, 0);
  b.resize(n, 0);
  fft(a, 0);
  fft(b, 0);
 
  for (int i = 0; i < n; i++) {
    a[i] *= b[i];
  }
  fft(a, 1);
  sol.clear();
 
  for (int i = 0; i < n; i++) {
    sol.push_back(a[i]);
  }
}
 
ld values[26];
 
const ld eps = 1e-6;
 
vector<cd> lol, cs, a;
vector<cd> reta, retb;
 
void place(string s, int len, vector<ld> &sol) {
  sol.clear();
  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);
  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'];
  }
  sol.resize(n - len + 1);
  conv_smart(cs, a, lol);
  for (int i = 0; i < n - len + 1; i++) {
    sol[i] = norm(lol[i + len - 1]);
  }
}
 
string s, t;
vector<ld> norms_s, norms_t;
 
bool isok(int len) {
  if (len > (int) s.size() || len > (int) t.size()) {
    return 0;
  }
  int n = (int) s.size() - len + 1;
  int m = (int) t.size() - len + 1;
  norms_s.resize(n);
  norms_t.resize(m);
  for (int i = 0; i < n; i++) {
    norms_s[i] = norm(reta[(len - 1) * ((int) s.size() + 2) + i]);
  }
  for (int i = 0; i < m; i++) {
    norms_t[i] = norm(retb[(len - 1) * ((int) t.size() + 2) + i]);
  }
  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) {
  int n = (int) s.size() - len + 1;
  int m = (int) t.size() - len + 1;
  norms_s.resize(n);
  norms_t.resize(m);
  for (int i = 0; i < n; i++) {
    norms_s[i] = norm(reta[(len - 1) * ((int) s.size() + 2) + i]);
  }
  for (int i = 0; i < m; i++) {
    norms_t[i] = norm(retb[(len - 1) * ((int) t.size() + 2) + i]);
  }
  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);
      }
    }
  }
}
 
vector<cd> cur;
 
void add(vector<cd> &v) {
  for (auto &x : v) {
    cur.push_back(x);
  }
}
 
int main() {
  for (int x = 0; x < 26; x++) {
    values[x] = cos(rng()) * 10;
  }
  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();
  for (int len = 1; len <= n; len++) {
    vector<cd> x(len);
    ld ang = 2 * PI / len;
    cd c(cos(ang), sin(ang));
    x[0] = 1;
    for (int i = 1; i < len; i++) {
      x[i] = x[i - 1] * c;
    }
    for (int i = 0; i <= n - len; i++) {
      x.push_back(0);
    }
    add(x);
  }
 
  {
    a.resize(n);
    for (int i = 0; i < n; i++) {
      a[i] = values[s[i] - 'a'];
    }
    conv_smart(a, cur, reta);
  }
 
  cur.clear();
 
  for (int len = 1; len <= m; len++) {
    vector<cd> x(len);
    ld ang = 2 * PI / len;
    cd c(cos(ang), sin(ang));
    x[0] = 1;
    for (int i = 1; i < len; i++) {
      x[i] = x[i - 1] * c;
    }
    for (int i = 0; i <= m - len; i++) {
      x.push_back(0);
    }
    add(x);
  }
 
  {
    a.resize(m);
    for (int i = 0; i < m; i++) {
      a[i] = values[t[i] - 'a'];
    }
    conv_smart(a, cur, retb);
  }
  for (int len = 1; len <= n; len++) {
    place(s, len, norms_s);
    for (int i = 0; i < n - len + 1; i++) {
      cd l = lol[i + len - 1] - reta[(len - 1) * (n + 2) + i];
 
      assert(abs(real(l)) < eps);
      assert(abs(imag(l)) < eps);
    }
  }
  int len = min(n, m);
  while (!isok(len)) {
    if (verbose) {
      cout << "len = " << len << "\n";
    }
    len--;
  }
  cout << len << "\n";
  print(len);
  return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

necklace.cpp: In function 'int main()':
necklace.cpp:184:13: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  184 |     freopen ("___input___.txt", "r", stdin);
      |     ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 25 / 25
• Subtask 2: 20 / 20
• Subtask 3: 0 / 40