Submission #425189

#	Time	Username	Problem	Language	Result	Execution time	Memory
425189		Mamnoon_Siam	Two Antennas (JOI19_antennas)	C++17	100 / 100	1109 ms	68936 KiB

antennas

// https://codeforces.com/blog/entry/66022?#comment-500622

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

using ll = long long;
using ii = pair<int, int>;
using vi = vector<int>;
#define all(v) begin(v), end(v)
#define sz(v) (int)(v).size()
#define fi first
#define se second

const int inf = 1e9 + 9;

/*struct Node {
  vector<int> c, d;
  Node(int _, int n) {
    c.assign(n, -inf);
    d.assign(n, -inf);
  }
  void update_ci(int pos, int val) {
    c[pos-1] = val;
  }
  void update_di(int L, int R, int val) {
    for(int i = L-1; i < R; ++i) {
      d[i] = max(d[i], c[i] + val);
    }
  }
  int get_max_di(int L, int R) {
    int ret = -inf;
    for(int i = L-1; i < R; ++i) {
      ret = max(ret, d[i]);
    } return ret;
  }
};*/

struct Node {
  Node *l = 0, *r = 0;
  int mx_di = -inf, mx_ci = -inf;
  int lo, hi;
  int lz = -2*inf;
  Node(int _lo, int _hi) : lo(_lo), hi(_hi) {
    if(lo < hi) {
      int mid = (lo + hi) >> 1;
      l = new Node(lo, mid);
      r = new Node(mid+1, hi);
    }
  }
  void upd(int val) {
    lz = max(lz, val);
    mx_di = (int)max((ll)mx_di, (ll)mx_ci + lz);
  }
  void push() {
    if(lo < hi) {
      l -> upd(lz);
      r -> upd(lz);
    }
    lz = -2*inf;
  }
  void update_ci(int pos, int ci) {
    if(lo == hi) {
      mx_ci = ci;
      lz = -2*inf;
    } else {
      push();
      if(pos <= l -> hi)
        l -> update_ci(pos, ci);
      else
        r -> update_ci(pos, ci);
      mx_ci = max(l -> mx_ci, r -> mx_ci);
    }
  }
  void update_di(int L, int R, int val) { // do d[i] max= c[i] + val, val negative in this problem
    if(hi < L or lo > R) return;
    if(L <= lo and hi <= R) {
      upd(val);
    } else {
      push();
      l -> update_di(L, R, val);
      r -> update_di(L, R, val);
      mx_di = max(l -> mx_di, r -> mx_di);
    }
  }
  int get_max_di(int L, int R) { // max{ d[i] | i \in [L, R] }
    if(hi < L or lo > R) return -inf;
    if(L <= lo and hi <= R) return mx_di;
    push();
    return max(l->get_max_di(L,R), r->get_max_di(L,R));
  }
};

const int N = 2e5 + 5;

int n, q;
int H[N], A[N], B[N];
int ans[N];
int L[N], R[N];

void solve() {
  vector<vi> offline(n+2), queries_w_R_at(n+1);
  for(int i = 1; i <= q; ++i) {
    queries_w_R_at[R[i]].emplace_back(i);
  }
  for(int i = 1; i <= n; ++i) {
    offline[min(n+1, i + A[i])].emplace_back(i);
    offline[min(n+1, i + B[i] + 1)].emplace_back(-i);
  }
  Node *tr = new Node(1, n);
  for(int i = 1; i <= n; ++i) {
    for(int j : offline[i]) {
      if(j < 0) { // del
        tr -> update_ci(-j, -inf);
      } else { // ins
        tr -> update_ci(j, H[j]);
      }
    }
    if(i - A[i] >= 1) {
      tr -> update_di(max(1, i - B[i]), i - A[i], -H[i]);
    }
    for(int j : queries_w_R_at[i]) {
      ans[j] = max(ans[j], tr -> get_max_di(L[j], R[j]));
    }
  }
}

int main(int argc, char const *argv[])
{
#ifdef LOCAL
  freopen("in", "r", stdin);
#endif
  fill(ans, ans+N, -inf);
  scanf("%d", &n);
  for(int i = 1; i <= n; ++i) {
    scanf("%d %d %d", &H[i], &A[i], &B[i]);
  }
  scanf("%d", &q);
  for(int i = 1; i <= q; ++i) {
    scanf("%d %d", &L[i], &R[i]);
  }
  solve();
  for(int i = 1, j = n; i < j; ++i, --j) {
    swap(H[i], H[j]);
    swap(A[i], A[j]);
    swap(B[i], B[j]);
  }
  for(int i = 1; i <= q; ++i) {
    L[i] = n - L[i] + 1;
    R[i] = n - R[i] + 1;
    swap(L[i], R[i]);
  }
  solve();
  for(int i = 1; i <= q; ++i) {
    printf("%d\n", ans[i] < 0 ? -1 : ans[i]);
  }
  return 0;
}
/*
* use std::array instead of std::vector, if u can
* overflow?
* array bounds
*/

Compilation message (stderr)

antennas.cpp: In function 'int main(int, const char**)':
antennas.cpp:133:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  133 |   scanf("%d", &n);
      |   ~~~~~^~~~~~~~~~
antennas.cpp:135:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  135 |     scanf("%d %d %d", &H[i], &A[i], &B[i]);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
antennas.cpp:137:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  137 |   scanf("%d", &q);
      |   ~~~~~^~~~~~~~~~
antennas.cpp:139:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  139 |     scanf("%d %d", &L[i], &R[i]);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 2 / 2
• Subtask 2: 11 / 11
• Subtask 3: 22 / 22
• Subtask 4: 65 / 65