Submission #980378

#	Time	Username	Problem	Language	Result	Execution time	Memory
980378		vjudge1	Rainforest Jumps (APIO21_jumps)	C++17	25 / 100	590 ms	1048576 KiB

jumps

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

using namespace std;
#define ll long long
const int mod = 1e9 + 7;
const int inf = 1e9;

template<typename T>
int len(T &a){return a.size();}

vector<int> lef, rig;
vector<vector<int>> g;
int n;
bool sub1 = 1;
vector<vector<int>> dis;

struct Segtree{
  vector<int> t;
  int n;
  void init(int _n){
    n = _n;
    t.resize(2 * n);
  }
  int merge(const int &a, const int &b){
    return min(a, b);
  }
  void build(vector<int> &a){
    init(len(a));
    for(int i = 0; i < n; i ++) t[i + n] = a[i];
    for(int i = n - 1; i > 0; i --) t[i] = merge(t[i << 1], t[i << 1 | 1]);
  }

  int get(int l, int r){
    l += n; r += n;
    int res = inf;
    while(l <= r){
      if(l % 2) res = merge(res, t[l ++]);
      if(r % 2 == 0) res = merge(res, t[r --]);
      l /= 2; r /= 2;
    }
    return res;
  }
};
vector<Segtree> t;


void init(int N, vector<int> h) {
  n = N;
  vector<int> st;
  lef.resize(n), rig.resize(n); g.resize(n);
  for(int i = 0; i < n; i ++){
    if(h[i] != i + 1) sub1 = 0;
    while(!st.empty() && h[st.back()] <= h[i]) st.pop_back();
    if(st.empty()) lef[i] = -1;
    else lef[i] = st.back();
    st.push_back(i);
  }
  if(sub1) return;
  
  t.resize(n);
  dis.assign(n, vector<int> (n, inf));
  st.clear();
  for(int i = n - 1; i >= 0; i --){
    while(!st.empty() && h[st.back()] <= h[i]) st.pop_back();
    if(st.empty()) rig[i] = n;
    else rig[i] = st.back();
    st.push_back(i);
  }

  for(int i = 0; i < n; i ++){
    if(~lef[i]) g[i].push_back(lef[i]);
    if(rig[i] != n) g[i].push_back(rig[i]);
  }

  auto bfs = [&](int beg){
    queue<int> q; q.push(beg);
    dis[beg][beg] = 0;
    while(!q.empty()){
      int f = q.front(); q.pop();
      for(auto u : g[f]){
        if(dis[beg][u] != inf) continue;
        dis[beg][u] = dis[beg][f] + 1;
        q.push(u);
      }
    }
  };  
  for(int i = 0; i < n; i ++){
    bfs(i);
    t[i].build(dis[i]);
  }

}

int minimum_jumps(int A, int B, int C, int D) {
  if(sub1) return C - B;
  int mn = inf;
  for(int i = A; i <= B; i ++) mn = min(mn, t[i].get(C, D));
  return (mn == inf ? -1 : mn);
}

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