Submission #572318

#	Time	Username	Problem	Language	Result	Execution time	Memory
572318		600Mihnea	Rainforest Jumps (APIO21_jumps)	C++17	33 / 100	4089 ms	19912 KiB

jumps

#include "jumps.h"
#include <bits/stdc++.h>

using namespace std;


const int N = 200000 + 7;
const int K = 20;
const int inf = (int) 1e9 + 7;
int n, a[N], lft[N], rgh[N], position[N], go[N], dist[N];
int rmq[K][N], lg2[N];

int getmax(int l, int r) {
  assert(1 <= l && l <= r && r <= n);
  int k = lg2[r - l + 1];
  return max(rmq[k][l], rmq[k][r - (1 << k) + 1]);
}

void init(int nn, vector<int> hh) {
  n = nn;

  assert(n == (int) hh.size());

  for (int i = 1; i <= n; i++) {
    a[i] = hh[i - 1];
    position[a[i]] = i;

    rmq[0][i] = a[i];
  }

  for (int i = 2; i <= n; i++) {
    lg2[i] = 1 + lg2[i / 2];
  }

  for (int k = 1; (1 << k) <= n; k++) {
    for (int i = 1; i + (1 << k) - 1 <= n; i++) {
      rmq[k][i] = max(rmq[k - 1][i], rmq[k - 1][i + (1 << (k - 1))]);
    }
  }


  {
    vector<int> stk;
    for (int i = 1; i <= n; i++) {
      while (!stk.empty() && a[stk.back()] <= a[i]) stk.pop_back();
      if (!stk.empty()) lft[i] = stk.back(); else lft[i] = 0;
      stk.push_back(i);
    }
  }
  {
    vector<int> stk;
    for (int i = n; i >= 1; i--) {
      while (!stk.empty() && a[stk.back()] <= a[i]) stk.pop_back();
      if (!stk.empty()) rgh[i] = stk.back(); else rgh[i] = 0;
      stk.push_back(i);
    }
  }
  for (int i = 1; i <= n; i++) {
    if (lft[i]) {
      assert(a[lft[i]] > a[i]);
    }
    if (rgh[i]) {
      assert(a[rgh[i]] > a[i]);
    }
  }

}

int minimum_jumps(int l1, int r1, int l2, int r2) {
  l1++;
  r1++;
  l2++;
  r2++;

  assert(1 <= l1 && l1 <= r1 && r1 < l2 && l2 <= r2 && r2 <= n);



  int ymax = getmax(l2, r2);
  l1 = max(l1, lft[position[ymax]] + 1);

  if (l1 > r1) {
    return -1;
  }

  for (int i = 1; i <= n; i++) {
    dist[i] = inf;
  }

  queue<int> Q;

  int mp = position[getmax(l1, r1)];

  for (int i = l1; i <= r1; i++) {
    if (i != mp) continue;
    dist[i] = 0;
    Q.push(i);
  }

  while (!Q.empty()) {
    int X = Q.front(), b = X;
    Q.pop();

    if (lft[X] && dist[lft[X]] == inf) {
      dist[lft[X]] = 1 + dist[X];
      Q.push(lft[X]);
    }

    if (rgh[X] && dist[rgh[X]] == inf) {
      dist[rgh[X]] = 1 + dist[X];
      Q.push(rgh[X]);
    }

  }

  int sol = inf;

  for (int i = 1; i <= n; i++) {
    if (rgh[i] && l2 <= rgh[i] && rgh[i] <= r2) {
      sol = min(sol, dist[i] + 1);
    }
  }


  if (sol == inf) {
    sol = -1;
  }

  return sol;
}

Compilation message (stderr)

jumps.cpp: In function 'int minimum_jumps(int, int, int, int)':
jumps.cpp:101:24: warning: unused variable 'b' [-Wunused-variable]
  101 |     int X = Q.front(), b = X;
      |                        ^

• Subtask 1: 0 / 4
• Subtask 2: 8 / 8
• Subtask 3: 13 / 13
• Subtask 4: 12 / 12
• Subtask 5: 0 / 23
• Subtask 6: 0 / 21
• Subtask 7: 0 / 19