Submission #425067

#	Time	Username	Problem	Language	Result	Execution time	Memory
425067		ollel	Boxes with souvenirs (IOI15_boxes)	C++14	50 / 100	42 ms	4084 KiB

boxes

#include <bits/stdc++.h>
#include <iostream>
#include "boxes.h"
using namespace std;
 
#define rep(i,a,b) for(int i = a; i < b; i++)
#define pb push_back
#define lso(x) x&(-x)
 
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
 
int n, k, l;
vi p;
vi pos;
 
ll min(ll a, int b) {return min(a, (ll)b);}
 
ll kone() {
  ll ans = 0;
  rep(i,0,n) {
    ans += 2*min(pos[i], l - pos[i]);
  }
  return ans;
}
 
ll kn() {
  ll ans = l;
  ans = min(ans, 2*(l - pos[0]));
  ans = min(ans, 2*pos[n - 1]);
  rep(i,0,n - 1) {
    ans = min(ans, 2*pos[i] + 2*(l - pos[i + 1]));
  }
  return ans;
}
 
ll solve(int start) {
  int a = 0, b = start;
  ll ans = 0;
  int fhc = l / 2;
  int shc = l / 2 + (l & 1);
 
  while (a < n) {
    if (pos[b] <= fhc) ans += 2*pos[b];
    else if (pos[a] >= shc) ans += 2*(l - pos[a]);
    else {
      int low = a, high = b + 1, c;
      while (high - low > 1) {
        c = (high + low) / 2;
        if (pos[c] >= shc) high = c;
        else low = c;
      }
      ll cand1 = l, cand2 = 2*pos[c] + 2*(l - pos[c + 1]);
      ans += min(cand1, cand2);
    }
 
    a = b + 1;
    b = min(a + k - 1, n - 1);
  }
  return ans;
}
 
ll get() {
  ll ans = 1e18;
  rep(i,0,k) ans = min(ans, solve(i));
  return ans;
}
 
ll delivery(int N, int K, int L, int positions[]) {
  n = N; k = K; l = L;
  if (n > 1e5 && n != k) exit(0);
  pos.resize(n); rep(i,0,n) pos[i] = positions[i];
  return get();
  if (k == 1) return kone();
  else if (k == n) return kn();
  else return get();
}

Compilation message (stderr)

boxes.cpp: In function 'll solve(int)':
boxes.cpp:54:36: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
   54 |       ll cand1 = l, cand2 = 2*pos[c] + 2*(l - pos[c + 1]);
      |                                    ^

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 15 / 15
• Subtask 4: 15 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 30