Submission #54267

# Submission time Handle Problem Language Result Execution time Memory
54267 2018-07-03T01:19:33 Z nimar Split the sequence (APIO14_sequence) C++11
100 / 100
1276 ms 86304 KB
#include <iostream>
#include <vector>
#include <unordered_map>
#include <map>
#include <utility>
#include <algorithm>
#include <list>
#include <limits>
#include <cassert>

typedef long long ll;
static std::vector<int> A;
static std::vector<long long> psum;
static int n, k;
static std::vector<std::vector<int>> offset; // (k+1) x (n+1) -> offset
static std::list<int> answer;

// assume a1 <= a2. Want smallest x(>=0) s.t. a2.x + b2 >= a1.x + b1
ll intersect(ll a1, ll b1, ll a2, ll b2) {
  if (a1 != a2) {
    ll x = (b1 - b2) / (a2 - a1);
    if ((a2 * x + b2) >= (a1 * x + b1))
      return x;
    else
      return x + 1;
  }

  if (b1 > b2)
    return std::numeric_limits<ll>::max();

  return 0LL;
}

static long long dp(void) {
  int k1;
  for (k1=0; k1<=k; k1++)
    offset.push_back(std::vector<int> (n+1, 0));

  std::vector<long long> prevrow(n+1, 0);
  std::vector<long long> row(n+1, 0);

  // k = 0 => all offsets are zero
  for (k1=1; k1<=k; k1++) {
    std::swap(row, prevrow);

    for (int i=2; i<=k1; i++)
      row[i] = 0LL;

    row[k1+1] = prevrow[k1] + psum[k1] * A[k1];
    offset[k1][k1+1] = k1;


    std::vector<ll> slopes;
    std::vector<ll> intercepts;
    std::vector<int> indices;
    std::vector<ll> xmins;

    slopes.push_back(psum[k1]);
    intercepts.push_back(- psum[k1] * psum[k1] + prevrow[k1]);
    indices.push_back(k1);
    xmins.push_back(0);

    int lastidx = 0; // remember the convex hull location for previous i

    for (int i=(k1+2); i<=n; i++) {
      // find j to maximize: prevrow[j] + psum[j] * (psum[i] - psum[j]);
      // j goes from k1 to i-1

      ll slope = psum[i-1];
      ll intercept = -psum[i-1] * psum[i-1] + prevrow[i-1];

      while (true) {
        ll x = intersect(slopes.back(), intercepts.back(), slope, intercept);
        if (x <= xmins.back()) {
          slopes.pop_back();
          intercepts.pop_back();
          indices.pop_back();
          xmins.pop_back();

          if (!slopes.empty())
            continue;
        }
        slopes.push_back(slope);
        intercepts.push_back(intercept);
        indices.push_back(i-1);
        xmins.push_back(x);
        break;
      }

      if (lastidx > (xmins.size() - 1))
        lastidx = xmins.size() - 1;

      int idx = lastidx;

      for (idx=lastidx; (idx+1) < xmins.size(); idx++) {
        if (psum[i] >= xmins[idx] and psum[i] < xmins[idx + 1])
          break;
      }
      int j = indices[idx];

      row[i] = prevrow[j] + psum[j] * (psum[i] - psum[j]);
      offset[k1][i] = j;
      lastidx = idx;
    }

    /*
    std::cout << "k " << k1 << " val ";
    for (long long x: row)
      std::cout << x << " ";
    std::cout << std::endl;
    std::cout << "k " << k1 << " off ";
    for (long x: offset[k1])
      std::cout << x << " ";
    std::cout << std::endl;
    */
  }

  int lastoffset = n;
  k1 = k;
  while (k1 > 0) {
    lastoffset = offset[k1][lastoffset];
    answer.push_front(lastoffset);
    k1 --;
  }

  return row[n];
}

int main(int argc, char const *argv[]) {
  std::cin >> n >> k;
  for (int i=0; i<n; i++) {
    int a;
    std::cin >> a;
    A.push_back(a);
  }
  psum.push_back(0);
  for (int i=0; i<n; i++)
    psum.push_back(A[i] + psum[i]);

  std::cout << dp() << std::endl;
  for (int a: answer)
    std::cout << a << " ";
  std::cout << std::endl;

  return 0;
}

Compilation message

sequence.cpp: In function 'long long int dp()':
sequence.cpp:90:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
       if (lastidx > (xmins.size() - 1))
           ~~~~~~~~^~~~~~~~~~~~~~~~~~~~
sequence.cpp:95:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
       for (idx=lastidx; (idx+1) < xmins.size(); idx++) {
                         ~~~~~~~~^~~~~~~~~~~~~~
# Verdict Execution time Memory Grader output
1 Correct 3 ms 504 KB contestant found the optimal answer: 108 == 108
2 Correct 2 ms 504 KB contestant found the optimal answer: 999 == 999
3 Correct 3 ms 572 KB contestant found the optimal answer: 0 == 0
4 Correct 3 ms 584 KB contestant found the optimal answer: 1542524 == 1542524
5 Correct 2 ms 584 KB contestant found the optimal answer: 4500000000 == 4500000000
6 Correct 2 ms 644 KB contestant found the optimal answer: 1 == 1
7 Correct 2 ms 644 KB contestant found the optimal answer: 1 == 1
8 Correct 2 ms 644 KB contestant found the optimal answer: 1 == 1
9 Correct 2 ms 644 KB contestant found the optimal answer: 100400096 == 100400096
10 Correct 2 ms 644 KB contestant found the optimal answer: 900320000 == 900320000
11 Correct 2 ms 644 KB contestant found the optimal answer: 3698080248 == 3698080248
12 Correct 2 ms 644 KB contestant found the optimal answer: 3200320000 == 3200320000
13 Correct 2 ms 644 KB contestant found the optimal answer: 140072 == 140072
14 Correct 2 ms 644 KB contestant found the optimal answer: 376041456 == 376041456
15 Correct 2 ms 644 KB contestant found the optimal answer: 805 == 805
16 Correct 3 ms 644 KB contestant found the optimal answer: 900189994 == 900189994
17 Correct 3 ms 644 KB contestant found the optimal answer: 999919994 == 999919994
# Verdict Execution time Memory Grader output
1 Correct 2 ms 644 KB contestant found the optimal answer: 1093956 == 1093956
2 Correct 2 ms 644 KB contestant found the optimal answer: 302460000 == 302460000
3 Correct 2 ms 644 KB contestant found the optimal answer: 122453454361 == 122453454361
4 Correct 2 ms 644 KB contestant found the optimal answer: 93663683509 == 93663683509
5 Correct 2 ms 644 KB contestant found the optimal answer: 1005304678 == 1005304678
6 Correct 2 ms 644 KB contestant found the optimal answer: 933702 == 933702
7 Correct 2 ms 644 KB contestant found the optimal answer: 25082842857 == 25082842857
8 Correct 2 ms 644 KB contestant found the optimal answer: 687136 == 687136
9 Correct 2 ms 644 KB contestant found the optimal answer: 27295930079 == 27295930079
10 Correct 2 ms 644 KB contestant found the optimal answer: 29000419931 == 29000419931
# Verdict Execution time Memory Grader output
1 Correct 2 ms 644 KB contestant found the optimal answer: 610590000 == 610590000
2 Correct 2 ms 644 KB contestant found the optimal answer: 311760000 == 311760000
3 Correct 3 ms 764 KB contestant found the optimal answer: 1989216017013 == 1989216017013
4 Correct 2 ms 764 KB contestant found the optimal answer: 1499437552673 == 1499437552673
5 Correct 3 ms 764 KB contestant found the optimal answer: 1019625819 == 1019625819
6 Correct 3 ms 764 KB contestant found the optimal answer: 107630884 == 107630884
7 Correct 4 ms 892 KB contestant found the optimal answer: 475357671774 == 475357671774
8 Correct 3 ms 892 KB contestant found the optimal answer: 193556962 == 193556962
9 Correct 2 ms 892 KB contestant found the optimal answer: 482389919803 == 482389919803
10 Correct 3 ms 892 KB contestant found the optimal answer: 490686959791 == 490686959791
# Verdict Execution time Memory Grader output
1 Correct 3 ms 892 KB contestant found the optimal answer: 21503404 == 21503404
2 Correct 3 ms 892 KB contestant found the optimal answer: 140412195 == 140412195
3 Correct 9 ms 1404 KB contestant found the optimal answer: 49729674225461 == 49729674225461
4 Correct 3 ms 1404 KB contestant found the optimal answer: 37485571387523 == 37485571387523
5 Correct 11 ms 1404 KB contestant found the optimal answer: 679388326 == 679388326
6 Correct 10 ms 1404 KB contestant found the optimal answer: 4699030287 == 4699030287
7 Correct 17 ms 1404 KB contestant found the optimal answer: 12418819758185 == 12418819758185
8 Correct 9 ms 1408 KB contestant found the optimal answer: 31093317350 == 31093317350
9 Correct 6 ms 1408 KB contestant found the optimal answer: 12194625429236 == 12194625429236
10 Correct 5 ms 1408 KB contestant found the optimal answer: 12345131038664 == 12345131038664
# Verdict Execution time Memory Grader output
1 Correct 7 ms 1408 KB contestant found the optimal answer: 1818678304 == 1818678304
2 Correct 5 ms 1408 KB contestant found the optimal answer: 1326260195 == 1326260195
3 Correct 161 ms 9404 KB contestant found the optimal answer: 4973126687469639 == 4973126687469639
4 Correct 8 ms 9404 KB contestant found the optimal answer: 3748491676694116 == 3748491676694116
5 Correct 67 ms 9404 KB contestant found the optimal answer: 1085432199 == 1085432199
6 Correct 72 ms 9404 KB contestant found the optimal answer: 514790755404 == 514790755404
7 Correct 97 ms 9404 KB contestant found the optimal answer: 1256105310476641 == 1256105310476641
8 Correct 95 ms 9404 KB contestant found the optimal answer: 3099592898816 == 3099592898816
9 Correct 102 ms 9404 KB contestant found the optimal answer: 1241131419367412 == 1241131419367412
10 Correct 165 ms 9404 KB contestant found the optimal answer: 1243084101967798 == 1243084101967798
# Verdict Execution time Memory Grader output
1 Correct 43 ms 9404 KB contestant found the optimal answer: 19795776960 == 19795776960
2 Correct 49 ms 9404 KB contestant found the optimal answer: 19874432173 == 19874432173
3 Correct 1149 ms 86304 KB contestant found the optimal answer: 497313449256899208 == 497313449256899208
4 Correct 54 ms 86304 KB contestant found the optimal answer: 374850090734572421 == 374850090734572421
5 Correct 1276 ms 86304 KB contestant found the optimal answer: 36183271951 == 36183271951
6 Correct 810 ms 86304 KB contestant found the optimal answer: 51629847150471 == 51629847150471
7 Correct 1043 ms 86304 KB contestant found the optimal answer: 124074747024496432 == 124074747024496432
8 Correct 814 ms 86304 KB contestant found the optimal answer: 309959349080800 == 309959349080800
9 Correct 930 ms 86304 KB contestant found the optimal answer: 124113525649823701 == 124113525649823701
10 Correct 1109 ms 86304 KB contestant found the optimal answer: 124309619349406845 == 124309619349406845