Submission #94572

#	Time	Username	Problem	Language	Result	Execution time	Memory
94572		wxh010910	Shortcut (IOI16_shortcut)	C++17	100 / 100	1397 ms	49724 KiB

shortcut

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

using namespace std;

const long long inf = 1ll << 60;

long long find_shortcut(int n, vector<int> l, vector<int> d, int c) {
  vector<long long> x(n);
  for (int i = 0; i < n - 1; ++i) {
    x[i + 1] = x[i] + l[i];
  }
  auto check = [&](long long limit) {
    long long lsum = -inf, rsum = inf;
    long long ldiff = -inf, rdiff = inf;
    long long max_sum = -inf, min_diff = inf;
    deque<int> q;
    for (int i = 0; i < n; ++i) {
      while (!q.empty() && x[i] - x[q.front()] + d[i] + d[q.front()] > limit) {
        max_sum = max(max_sum, x[q.front()] + d[q.front()]);
        min_diff = min(min_diff, x[q.front()] - d[q.front()]);
        q.pop_front();
      }
      if (max_sum >= 0) {
        lsum = max(lsum, x[i] + d[i] + max_sum + c - limit);
        rsum = min(rsum, x[i] - d[i] + min_diff + limit - c);
        rdiff = min(rdiff, x[i] - d[i] - max_sum + limit - c);
        ldiff = max(ldiff, x[i] + d[i] - min_diff + c - limit);
      }
      while (!q.empty() && x[i] - d[i] < x[q.back()] - d[q.back()]) {
        q.pop_back();
      }
      q.push_back(i);
    }
    if (lsum > rsum || ldiff > rdiff) {
      return false;
    }
    for (int i = 0, j = n, k = 0; i < n; ++i) {
      while (j && x[j - 1] + x[i] >= lsum) {
        --j;
      }
      while (k < n && x[k] - x[i] < ldiff) {
        ++k;
      }
      int p = max(i + 1, max(j, k));
      if (p < n && x[p] + x[i] <= rsum && x[p] - x[i] <= rdiff) {
        return true;
      }
    }
    return false;
  };
  long long low = 0, high = inf;
  while (low < high) {
    long long mid = low + high >> 1;
    if (check(mid)) {
      high = mid;
    } else {
      low = mid + 1;
    }
  }
  return high;
}

Compilation message (stderr)

shortcut.cpp: In function 'long long int find_shortcut(int, std::vector<int>, std::vector<int>, int)':
shortcut.cpp:54:25: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
     long long mid = low + high >> 1;
                     ~~~~^~~~~~

• 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: 3 / 3