제출 #1041721

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1041721		abczz	Chorus (JOI23_chorus)	C++17	40 / 100	7072 ms	860 KiB

chorus

#include <iostream>
#include <algorithm>
#include <deque>
#include <vector>
#include <array>
#define ll long long

using namespace std;

ll n, k, dp[2][5000];
vector <ll> A, B, nxA, ps;
string S;

ll C(ll l, ll r) {
  if (nxA[l] > r) return 0;
  ll nx = max(l, nxA[l]), cnt = r-nx+1, cnt2 = max(0LL, l-nxA[l]);
  return ps[r]-(nx ? ps[nx-1] : 0)-cnt*B[l]-cnt*(cnt-1)/2-(r-l+1)*cnt2;
}

void solve(ll l, ll r, ll ql, ll qr) {
  ll mid = (l+r)/2;
  ll opt = 1e18, optid = -1, tmp;
  for (int i=ql; i<mid; ++i) {
    tmp = dp[0][i] + C(i+1, mid);
    if (opt > tmp) {
      opt = tmp;
      optid = i;
    }
  }
  dp[1][mid] = opt;
  if (l < mid) solve(l, mid-1, ql, optid);
  if (mid < r) solve(mid+1, r, optid, qr);
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(0);
  cin >> n >> k >> S;
  for (int i=0; i<2*n; ++i) {
    if (S[i] == 'A') {
      ps.push_back((ps.empty() ? 0 : ps.back()) + i);
      A.push_back(i);
    }
    else {
      B.push_back(i);
      nxA.push_back(A.size());
    }
  }
  for (int i=0; i<n; ++i) dp[0][i] = C(0, i);
  for (int x=1; x<k; ++x) {
    solve(0, n-1, 0, n-1);
    swap(dp[0], dp[1]);
  }
  cout << dp[0][n-1] << '\n';
}

• Subtask 1: 16 / 16
• Subtask 2: 24 / 24
• Subtask 3: 0 / 21
• Subtask 4: 0 / 26
• Subtask 5: 0 / 13