Submission #1014819

#	Time	Username	Problem	Language	Result	Execution time	Memory
1014819		MilosMilutinovic	Shortcut (IOI16_shortcut)	C++14	97 / 100	2056 ms	111804 KiB

shortcut

#include "shortcut.h"
#include <bits/stdc++.h>

using namespace std;

long long find_shortcut(int n, vector<int> l, vector<int> d, int c) {
  vector<long long> x(n);
  for (int i = 1; i < n; i++) {
    x[i] = x[i - 1] + l[i - 1];
  }
  vector<vector<long long>> val(n, vector<long long>(2));
  for (int i = 0; i < n; i++) {
    val[i][0] = x[i] + d[i];
    val[i][1] = x[i] - d[i];
  }
  vector<vector<int>> order(2, vector<int>(n));
  for (int t = 0; t < 2; t++) {
    iota(order[t].begin(), order[t].end(), 0);
    sort(order[t].begin(), order[t].end(), [&](int i, int j) {
      return (t == 0 ? val[i][0] < val[j][0] : val[i][1] < val[j][1]);
    });
  }
  const long long inf = (long long) 1e18;
  auto Check = [&](long long diam) {
    long long xl = -inf, xr = inf;
    long long yl = -inf, yr = inf;
    vector<pair<int, int>> mn(2, {-1, -1});
    vector<pair<int, int>> mx(2, {-1, -1});
    auto Update = [&](int i) {
      if (mn[0].first == -1 || val[i][0] < val[mn[0].first][0]) {
        swap(mn[0].first, mn[0].second);
        mn[0].first = i;
      } else if (mn[0].second == -1 || val[i][0] < val[mn[0].second][0]) {
        mn[0].second = i;
      }

      if (mn[1].first == -1 || val[i][1] < val[mn[1].first][1]) {
        swap(mn[1].first, mn[1].second);
        mn[1].first = i;
      } else if (mn[1].second == -1 || val[i][1] < val[mn[1].second][1]) {
        mn[1].second = i;
      }

      if (mx[0].first == -1 || val[i][0] > val[mx[0].first][0]) {
        swap(mx[0].first, mx[0].second);
        mx[0].first = i;
      } else if (mx[0].second == -1 || val[i][0] > val[mx[0].second][0]) {
        mx[0].second = i;
      }

      if (mx[1].first == -1 || val[i][1] > val[mx[1].first][1]) {
        swap(mx[1].first, mx[1].second);
        mx[1].first = i;
      } else if (mx[1].second == -1 || val[i][1] > val[mx[1].second][1]) {
        mx[1].second = i;
      }
    };
    int ptr = 0;
    for (int _i = 0; _i < n; _i++) {
      int i = order[0][_i];
      while (ptr < n && val[i][0] - val[order[1][ptr]][1] > diam) {
        Update(order[1][ptr]);
        ptr += 1;
      }
      
      if (mx[0].first != i && mx[0].first != -1) {
        xl = max(xl, val[i][0] - diam + c + val[mx[0].first][0]);
      } else if (mx[0].second != -1) {
        xl = max(xl, val[i][0] - diam + c + val[mx[0].second][0]);
      }

      if (mn[1].first != i && mn[1].first != -1) {
        xr = min(xr, val[i][1] + diam - c + val[mn[1].first][1]);
      } else if (mn[1].second != -1) {
        xr = min(xr, val[i][1] + diam - c + val[mn[1].second][1]);
      }

      if (mn[1].first != i && mn[1].first != -1) {
        yl = max(yl, val[i][0] - diam + c - val[mn[1].first][1]);
      } else if (mn[1].second != -1) {
        yl = max(yl, val[i][0] - diam + c - val[mn[1].second][1]);
      }

      if (mx[0].first != i && mx[0].first != -1) {
        yr = min(yr, val[i][1] + diam - c - val[mx[0].first][0]);
      } else if (mx[0].second != -1) {
        yr = min(yr, val[i][1] + diam - c - val[mx[0].second][0]);
      }
    }
    int plx = n, prx = n - 1, ply = 0, pry = -1;
    for (int i = 0; i < n; i++) {
      while (plx > 0 && x[i] + x[plx - 1] >= xl) {
        plx--;
      }
      while (prx >= 0 && x[i] + x[prx] > xr) {
        prx--;
      }
      while (ply < n && x[ply] - x[i] < yl) {
        ply++;
      }
      while (pry + 1 < n && x[pry + 1] - x[i] <= yr) {
        pry++;
      }
      int L = max({i + 1, plx, ply}), R = min(prx, pry);
      if (L <= R) {
        return true;
      }
    }
    return false;
  };  
  long long low = 0, high = inf, ans = 0;
  while (low <= high) {
    long long mid = (low + high) >> 1;
    if (Check(mid)) {
      ans = mid;
      high = mid - 1;
    } else {
      low = mid + 1;
    }
  }
  return ans;
}

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