Submission #654724

#	Time	Username	Problem	Language	Result	Execution time	Memory
654724		Sam_a17	Rainforest Jumps (APIO21_jumps)	C++14	100 / 100	2690 ms	64220 KiB

jumps

#include <bits/stdc++.h>
using namespace std;
 
#define dbg(x) cerr << #x << " " << x << endl;
#define ll long long

const int maxN = 2e5 + 10, LOG = 22, inf = 1e8;
int h[maxN], n, pre[maxN][LOG], nxt[maxN][LOG];
int mx[maxN][LOG];

struct segTree {
  vector<pair<long long, int>> mTree;
  int size;

  void init(long long n) {
    size = 1;
    while(size < n)  {
      size *= 2;
    }
    mTree.assign(2 * size - 1, {0, 0});
  }

  pair<ll, ll> combine(pair<ll, ll> a, pair<ll, ll> b) {
    if(a.first > b.first) {
      return a;
    } else {
      return b;
    }
  }

  void upd(int u, long long v, int x, int lx, int rx) { // set value at pos u
    if(rx - lx == 1) {
      mTree[x] = {v, lx};
      return;
    }

    int m = (lx + rx) / 2;
    if(u < m) {
      upd(u, v, 2 * x + 1, lx, m);
    }else {
      upd(u, v, 2 * x + 2, m, rx);
    }
    mTree[x] = combine(mTree[2 * x + 1], mTree[2 * x + 2]);
  }

  void upd(int u, long long v) {
    upd(u, v, 0, 0, size);
  }

  pair<ll, ll> qry (int l, int r, int x, int lx, int rx) { // range queries
    if(l >= rx || lx >= r) {
      return {INT64_MIN, -1};
    }
    if(lx >= l && r >= rx) {
      return mTree[x];
    }

    int m = (rx + lx) / 2;
    auto s1 = qry(l, r, 2 * x + 1, lx, m);
    auto s2 = qry(l, r, 2 * x + 2, m, rx);
    return combine(s1, s2);
  }

  pair<ll, ll> qry(int l, int r) {
    return qry(l, r, 0, 0, size);
  }
};

segTree seg;

void init(int N, std::vector<int> H) {
  n = N, seg.init(n + 1);
  for(int i = 0; i < N; i++) {
    h[i] = H[i];
    seg.upd(i, h[i]);
 
    //
    nxt[i][0] = pre[i][0] = i;
  }
 
  stack<pair<int, int>> st;
  for(int i = 0; i < N; i++) {
    while(!st.empty() && h[i] > st.top().first) {
      nxt[st.top().second][0] = i;
      st.pop();
    }
    st.push({h[i], i});
  }
 
  while(!st.empty()) st.pop();
 
  for(int i = N - 1; i >= 0; i--) {
    while(!st.empty() && h[i] > st.top().first) {
      pre[st.top().second][0] = i;
      st.pop();
    }
    st.push({h[i], i});
  }

  for(int i = 0; i < N; i++) {
    if(h[nxt[i][0]] >= h[pre[i][0]]) {
      mx[i][0] = nxt[i][0];
    } else {
      mx[i][0] = pre[i][0];
    }
  }

  for(int j = 1; j < LOG; j++) {
    for(int i = 0; i < N; i++) {
      mx[i][j] = mx[mx[i][j - 1]][j - 1];
      nxt[i][j] = nxt[nxt[i][j - 1]][j - 1];
      pre[i][j] = pre[pre[i][j - 1]][j - 1];
    }
  }
}
 
int get_mx(int mid, int node) {
  for(int i = 0; i < LOG; i++) {
    if(mid & (1 << i)) {
      node = mx[node][i];
    }
  }
  return node;
}

int get_r(int mid, int node) {
  for(int i = 0; i < LOG; i++) {
    if(mid & (1 << i)) {
      node = nxt[node][i];
    }
  }
  return node;
}

int minimum_jumps(int A, int B, int C, int D) {
  auto maxim = seg.qry(B, C);
  auto maxim_ = seg.qry(C, D + 1);
  if(maxim.first >= maxim_.first) {
    return -1;
  }

  int l = A, r = B, st = -1;
  while(l <= r) {
    int mid = (l + r) / 2;
    if(seg.qry(mid, r + 1).first < maxim_.first) {
      st = mid;
      r = mid - 1;
    } else {
      l = mid + 1;
    }
  }

  if(st == -1) {
    return -1;
  }

  A = seg.qry(st, B + 1).second;

  int ina = 0, inb = maxN, answ = 0;
  while(ina <= inb) {
    int mid = (ina + inb) / 2;
    int pos = get_mx(mid, A);
    if(h[pos] >= maxim.first) {
      answ = mid;
      inb = mid - 1;
    } else {
      ina = mid + 1;
    }
  }

  int pos = get_mx(answ, A);
  if(pos >= C && pos <= D) return answ;
  if(h[pos] >= maxim_.first) { answ--; }

  pos = get_mx(answ, A);

  ina = 0, inb = maxN;
  int answ2 = 0;
  while(ina <= inb) {
    int mid = (ina + inb) / 2;
    int pos2 = get_r(mid, pos);
    if(pos2 >= C) {
      answ2 = mid;
      inb = mid - 1;
    } else {
      ina = mid + 1;
    }
  }

  pos = get_r(answ2, pos);
  return answ2 + answ;
}

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 13 / 13
• Subtask 4: 12 / 12
• Subtask 5: 23 / 23
• Subtask 6: 21 / 21
• Subtask 7: 19 / 19