Submission #244884

#	Time	Username	Problem	Language	Result	Execution time	Memory
244884		rama_pang	Collecting Stamps 3 (JOI20_ho_t3)	C++14	25 / 100	2057 ms	147928 KiB

ho_t3

#include <bits/stdc++.h>
using namespace std;

using lint = long long;
const int MAXN = 205;

int N, L;
int X[MAXN], T[MAXN];
lint dist[MAXN][MAXN][2][MAXN];

struct State {
  int left;
  int right;
  int pos_right;
  int stamps;
  State() {}
  State(int l, int r, int p, int s) : left(l), right(r), pos_right(p), stamps(s) {}
  bool operator < (const State &o) const {
    return stamps < o.stamps;
  }
};

int Distance(int a, int b) {
  if (a > b) swap(a, b);
  return min(X[b] - X[a], X[a] + L - X[b]);
}

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  memset(dist, -1, sizeof(dist));

  cin >> N >> L;
  for (int i = 1; i <= N; i++) {
    cin >> X[i];
  }
  X[N + 1] = L;
  for (int i = 1; i <= N; i++) {
    cin >> T[i];
  }
  priority_queue<pair<lint, State>, vector<pair<lint, State>>, greater<pair<lint, State>>> pq;
  pq.emplace(0, State(0, N + 1, 0, 0));
  dist[0][N + 1][0][0] = 0;
  int ans = 0;
  while (!pq.empty()) {
    int left = pq.top().second.left;
    int right = pq.top().second.right;
    int pos_right = pq.top().second.pos_right;
    int stamps = pq.top().second.stamps;
    lint dt = pq.top().first;
    pq.pop();
    ans = max(ans, stamps);
    if (left > right || dist[left][right][pos_right][stamps] != dt) {
      continue;
    }
    int cur = pos_right ? right : left;
    if (left + 1 < right) {
      lint &nxt = dist[left + 1][right][0][stamps + (dt + Distance(left + 1, cur) <= T[left + 1])];
      if (nxt == -1 || nxt > dt + Distance(left + 1, cur)) {
        nxt = dt + Distance(left + 1, cur);
        pq.emplace(nxt, State(left + 1, right, 0, stamps + (dt + Distance(left + 1, cur) <= T[left + 1])));
      }
    }
    if (left < right - 1) {
      lint &nxt = dist[left][right - 1][1][stamps + (dt + Distance(right - 1, cur) <= T[right - 1])];
      if (nxt == -1 || nxt > dt + Distance(right - 1, cur)) {
        nxt = dt + Distance(right - 1, cur);
        pq.emplace(nxt, State(left, right - 1, 1, stamps + (dt + Distance(right - 1, cur) <= T[right - 1])));
      }
    }
  }
  cout << ans << "\n";
  return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 0 / 75