Submission #979716

#	Time	Username	Problem	Language	Result	Execution time	Memory
979716		nnin	Rainforest Jumps (APIO21_jumps)	C++14	81 / 100	4014 ms	45420 KiB

jumps

#include "jumps.h"
#include <bits/stdc++.h>
#define pii pair<int,int>
using namespace std;

int n, l[200005], r[200005], jump[200005][20], jump2[200005][20];
vector<int> h;
bool one;

struct segTree {
  pii seg[4*200005];

  void build(int i, int l, int r) {
    if(l==r) {
      seg[i] = {h[l], l};
      return;
    }
    int m = (l+r)/2;
    build(i*2+1, l, m);
    build(i*2+2, m+1, r);
    seg[i] = max(seg[i*2+1], seg[i*2+2]);
  }

  pii query(int i, int l, int r, int wl, int wr) {
    if(wl>r || wr<l) return {-2e9, -1};
    if(wl<=l && wr>=r) return seg[i];
    int m = (l+r)/2;
    return max(query(i*2+1, l, m, wl, wr), query(i*2+2, m+1, r, wl, wr));
  }
}t;

void init(int N, std::vector<int> H) {
  n = N;
  h = H;
  stack<int> st;
  for(int i=0;i<n;i++) {
    while(!st.empty() && H[st.top()]<H[i]) st.pop();
    if(st.empty()) l[i] = -1;
    else l[i] = st.top();
    st.push(i);
  }
  while(!st.empty()) st.pop();
  for(int i=n-1;i>=0;i--) {
    while(!st.empty() && H[st.top()]<H[i]) st.pop();
    if(st.empty()) r[i] = n;
    else r[i] = st.top();
    st.push(i);
  }
  t.build(0, 0, n-1);
  h.push_back(n+1);
  for(int i=0;i<n;i++) {
    int mx = l[i], mx2 = r[i];
    if(mx==-1) mx = n;
    if(h[mx]<h[mx2]) swap(mx, mx2);
    jump[i][0] = mx;
    jump2[i][0] = mx2;
  }
  jump[n][0] = jump2[n][0] = n;
  for(int j=1;j<20;j++) for(int i=0;i<=n;i++) jump[i][j] = jump[jump[i][j-1]][j-1];
  for(int j=1;j<20;j++) for(int i=0;i<=n;i++) jump2[i][j] = jump2[jump2[i][j-1]][j-1];
  one = 1;
  for(int i=0;i<n;i++) if(H[i]!=i+1) {
    one = 0;
    break;
  }
}

int subtask3(int A, int B, int C, int D) {
  vector<int> mindis(n, 2e9);
  priority_queue<pii, vector<pii>, greater<pii>> pq;
  for(int i=A;i<=B;i++) {
    mindis[i] = 0;
    pq.push({0, i});
  }
  while(!pq.empty()) {
    auto [dis, u] = pq.top();
    pq.pop();
    if(mindis[u]!=dis) continue;
    if(u>=C && u<=D) return dis;
    if(l[u]>=0) {
      if(mindis[l[u]]>dis+1) {
        mindis[l[u]] = dis+1;
        pq.push({dis+1, l[u]});
      }
    }
    if(r[u]<n) {
      if(mindis[r[u]]>dis+1) {
        mindis[r[u]] = dis+1;
        pq.push({dis+1, r[u]});
      }
    }
  }
  return -1;
}

int subtask5(int A, int B, int C) {
  A = t.query(0, 0, n-1, max(A, l[C]+1), min(B, r[C]-1)).second;
  if(A==-1) return -1;
  int ans = 0;
  for(int i=19;i>=0;i--) if(h[jump[A][i]]<h[C]) {
    A = jump[A][i];
    ans += (1<<i);
  }
  if(jump[A][0]==C) return ans+1;
  for(int i=19;i>=0;i--) if(h[jump2[A][i]]<h[C]) {
    A = jump2[A][i];
    ans += (1<<i);
  }
  if(jump2[A][0]==C) return ans+1;
  return -1;
}

int minimum_jumps(int A, int B, int C, int D) {
  if(C==D) return subtask5(A, B, C);
  if(one) return C-B;
  return subtask3(A, B, C, D);
}

Compilation message (stderr)

jumps.cpp: In function 'int subtask3(int, int, int, int)':
jumps.cpp:76:10: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   76 |     auto [dis, u] = pq.top();
      |          ^

• 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: 0 / 19