Submission #320406

#	Time	Username	Problem	Language	Result	Execution time	Memory
320406		VROOM_VARUN	Shortcut (IOI16_shortcut)	C++14	0 / 100	2090 ms	384 KiB

shortcut

/*
ID: varunra2
LANG: C++
TASK: shortcut
*/

#include <bits/stdc++.h>
#include "shortcut.h"
using namespace std;

#ifdef DEBUG
#include "lib/debug.h"
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define debug_arr(...) \
  cerr << "[" << #__VA_ARGS__ << "]:", debug_arr(__VA_ARGS__)
#pragma GCC diagnostic ignored "-Wsign-compare"
//#pragma GCC diagnostic ignored "-Wunused-parameter"
//#pragma GCC diagnostic ignored "-Wunused-variable"
#else
#define debug(...) 42
#endif

#define int long long

#define EPS 1e-9
#define IN(A, B, C) assert(B <= A && A <= C)
#define INF (int)1e3
#define MEM(a, b) memset(a, (b), sizeof(a))
#define MOD 1000000007
#define MP make_pair
#define PB push_back
#define all(cont) cont.begin(), cont.end()
#define rall(cont) cont.end(), cont.begin()
#define x first
#define y second

const double PI = acos(-1.0);
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef map<int, int> MPII;
typedef multiset<int> MSETI;
typedef set<int> SETI;
typedef set<string> SETS;
typedef vector<int> VI;
typedef vector<PII> VII;
typedef vector<VI> VVI;
typedef vector<string> VS;

#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define trav(a, x) for (auto& a : x)
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
typedef vector<int> vi;
#pragma GCC diagnostic ignored "-Wsign-compare"
// util functions

VI l;
VI x;
VI d;
VII ord;
vector<bool> dom;
VI doms;
int n;
int c;

void cop(VI& a, vector<int32_t> b) {
  a.resize(sz(b));
  for (int i = 0; i < sz(a); i++) {
    a[i] = b[i];
  }
}

void genPref() {
  x.resize(n);
  x[0] = 0ll;
  for (int i = 1; i < n; i++) {
    x[i] = x[i - 1] + l[i - 1];
  }
}

void genDom() {
  // here we need to generate statinos that are not dominated by anybody
  // then x[dom[i]] + d[dom[i]] is non decreasing
  dom.assign(n, true);
  // to do this, we need to generate prefix and suffix maxima of stuff lol
  int mx = -INF;
  for (int i = 0; i < n; i++) {
    int cur = d[i] + x[i];
    mx = max(mx, cur);
    if (cur < mx) dom[i] = false;
  }
  mx = -INF;
  for (int i = n - 1; i >= 0; i--) {
    int cur = d[i] - x[i];
    mx = max(mx, cur);
    if (cur < mx) dom[i] = false;
  }
  for (int i = 0; i < n; i++) {
    if (dom[i]) doms.PB(i);
  }
  assert(!doms.empty());
}

void genOrd() {
  // we also need to generate a sorted vector of pairs that contains when the
  // ith element is introduced, and its index
  ord.resize(n);
  for (int i = 0; i < n; i++) {
    ord[i] = MP(x[i] - d[i], i);
  }
  sort(all(ord));
}

int mnsum, mxsum, mndif, mxdif;

void upd(int i) {
  int x = ::x[i], d = ::d[i];
  int sum = x + d, dif = x - d;
  mnsum = min(mnsum, sum);
  mxsum = max(mxsum, sum);
  mndif = min(mndif, dif);
  mxdif = max(mxdif, dif);
}

const int bad = 92;

void initsumdif() {
  mnsum = INF;
  mxsum = -INF;
  mndif = INF;
  mxdif = -INF;
}

bool works(int k) {
  VI vals = {INF, -INF, INF, -INF};
  initsumdif();
  int p1 = 0;
  // for (int i = 0; i < n; i++) {
  //   if (dom[i] == false) continue;
  //   while (p1 < n and (ord[p1].x < x[i] + d[i] - k and ord[p1].y <= i)) {
  //     // now we process it
  //     upd(p1);
  //     p1++;
  //   }
  //   int sum = x[i] + d[i], dif = x[i] - d[i];
  //   vals[0] = min(vals[0], (k - c) + dif + mndif);
  //   vals[1] = max(vals[1], sum + mxsum - (k - c));
  //   vals[2] = min(vals[2], (k - c) + dif - mxsum);
  //   vals[3] = max(vals[3], sum - mndif - (k - c));
  // }

    for(int i = 0; i < n; i++) {
      initsumdif();
      for(int j = 0; j < i; j++) {
        if(x[i] + d[i] - (x[j] - d[j]) > k) upd(j);
      }
      int sum = x[i] + d[i], dif = x[i] - d[i];
      vals[0] = min(vals[0], (k - c) + dif + mndif);
      vals[1] = max(vals[1], sum + mxsum - (k - c));
      vals[2] = min(vals[2], (k - c) + dif - mxsum);
      vals[3] = max(vals[3], sum - mndif - (k - c));
    }

  // now we need to find two points in the rectangle defined by vals
  int maxsum, minsum, maxdif, mindif;
  maxsum = vals[0];
  minsum = vals[1];
  maxdif = vals[2];
  mindif = vals[3];
  debug(maxsum, minsum, maxdif, mindif, k);
  int curdif = 0;
  int cursum = n;
  if (maxsum < minsum or maxdif < mindif) return 0;
  for (int i = 0; i < n; i++) {
    while (curdif < n and x[curdif] - x[i] < mindif) curdif++;
    while (cursum > 0 and x[cursum - 1] + x[i] >= minsum) cursum--;
    int cur = max({cursum, curdif, i + 1});
    if (cur < n and x[cur] + x[i] <= maxsum and x[cur] - x[i] <= maxdif)
      return true;
  }
  // for(int i = 0; i < n; i++) {
  // for(int j = 0; j < i; j++) {
  // int sum = x[i] + x[j];
  // int dif = x[i] - x[j];
  // if(sum >= minsum and sum <= maxsum and dif >= mindif and dif <= maxdif)
  // return true;
  // }
  // }
  return false;
}

ll find_shortcut(int32_t _n, vector<int32_t> _l, vector<int32_t> _d,
                 int32_t _c) {
  n = _n;
  c = _c;
  cop(l, _l);
  cop(d, _d);
  genPref();
  genDom();
  genOrd();
  // debug(dom);
  debug(doms);
  debug(ord);
  int xx = -1;
  int z = INF;
  for (int b = z; b >= 1; b /= 2) {
    while (!works(xx + b)) xx += b;
  }
  return xx + 1;
}

// int32_t main() {
// #ifndef ONLINE_JUDGE
//   freopen("shortcut.in", "r", stdin);
//   freopen("shortcut.out", "w", stdout);
// #endif
//   cin.sync_with_stdio(0);
//   cin.tie(0);

//   int n, c;
//   cin >> n >> c;

//   vector<int32_t> l(n - 1);
//   vector<int32_t> d(n);

//   for (int i = 0; i < n - 1; i++) {
//     cin >> l[i];
//   }

//   for (int i = 0; i < n; i++) {
//     cin >> d[i];
//   }

//   cout << find_shortcut(n, l, d, c) << '\n';

//   return 0;
// }

Compilation message (stderr)

shortcut.cpp: In function 'bool works(long long int)':
shortcut.cpp:20:20: warning: statement has no effect [-Wunused-value]
   20 | #define debug(...) 42
      |                    ^~
shortcut.cpp:171:3: note: in expansion of macro 'debug'
  171 |   debug(maxsum, minsum, maxdif, mindif, k);
      |   ^~~~~
shortcut.cpp:138:7: warning: unused variable 'p1' [-Wunused-variable]
  138 |   int p1 = 0;
      |       ^~
shortcut.cpp: In function 'll find_shortcut(int32_t, std::vector<int>, std::vector<int>, int32_t)':
shortcut.cpp:20:20: warning: statement has no effect [-Wunused-value]
   20 | #define debug(...) 42
      |                    ^~
shortcut.cpp:203:3: note: in expansion of macro 'debug'
  203 |   debug(doms);
      |   ^~~~~
shortcut.cpp:20:20: warning: statement has no effect [-Wunused-value]
   20 | #define debug(...) 42
      |                    ^~
shortcut.cpp:204:3: note: in expansion of macro 'debug'
  204 |   debug(ord);
      |   ^~~~~

• Subtask 1: 0 / 9
• Subtask 2: 0 / 14
• Subtask 3: 0 / 8
• Subtask 4: 0 / 7
• Subtask 5: 0 / 33
• Subtask 6: 0 / 22
• Subtask 7: 0 / 4
• Subtask 8: 0 / 3