Submission #541968

#	Time	Username	Problem	Language	Result	Execution time	Memory
541968		aryan12	Rainforest Jumps (APIO21_jumps)	C++17	69 / 100	1089 ms	48572 KiB

jumps

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

const int MAXN = 2e5 + 5;
int DP_Min[19][MAXN], DP_Max[19][MAXN];
int seg[MAXN * 4];
vector<int> INPUT;
vector<int> g[MAXN];
vector<int> omk(MAXN);
int okN;

void Build(int l, int r, int pos) {
  if(l == r) {
    seg[pos] = INPUT[l - 1];
    return;
  }
  int mid = (l + r) >> 1;
  Build(l, mid, pos * 2);
  Build(mid + 1, r, pos * 2 + 1);
  seg[pos] = max(seg[pos * 2], seg[pos * 2 + 1]);
}

pair<int, int> Query(int l, int r, int pos, int ql, int qr, int qval) {
  if(ql > r || l > qr) {
    //cout << "l = " << l << ", r = " << r << ", there {-1, -1}\n";
    return {0, 0};
  }
  if(l == r) {
    if(seg[pos] >= qval) {
      //cout << "l = " << l << ", r = " << r << ", here {-1, -1}\n";
      return {-1, -1};
    }
    //cout << "l = " << l << ", r = " << r << ", {" << seg[pos] << ", " << seg[pos] << "}\n";
    return {seg[pos], seg[pos]};
  }
  if(ql <= l && r <= qr && seg[pos] < qval) {
    return {seg[pos], seg[pos]};
  }
  int mid = (l + r) >> 1;
  pair<int, int> x = Query(mid + 1, r, pos * 2 + 1, ql, qr, qval);
  if(x.second == -1) {
    //cout << "l = " << l << ", r = " << r << ", aftermid {" << x.first << ", -1}\n";
    return x;
  }
  pair<int, int> y = Query(l, mid, pos * 2, ql, qr, qval);
  if(y.second == -1) {
    //cout << "l = " << l << ", r = " << r << ", {" << max(y.first, x.first) << ", " << y.second << "}\n";
    return {max(y.first, x.first), -1};
  }
  //cout << "l = " << l << ", r = " << r << ", {" << max(y.first, x.first) << ", " << max(y.second, x.second) << "}\n";
  return {max(y.first, x.first), max(y.second, x.second)};
}

void init(int N, vector<int> H) {
  okN = N;
  vector<int> L(N), R(N);
  stack<int> q;
  for(int i = 0; i < N; i++) {
    omk[H[i]] = i;
    INPUT.push_back(H[i]);
    while(!q.empty() && H[q.top()] <= H[i]) {
      q.pop();
    }
    if(q.empty()) {
      L[i] = -1;
    }
    else {
      L[i] = q.top();
    }
    q.push(i);
  }
  Build(1, N, 1);
  while(!q.empty()) {
    q.pop();
  }
  for(int i = N - 1; i >= 0; i--) {
    while(!q.empty() && H[q.top()] <= H[i]) {
      q.pop();
    }
    if(q.empty()) {
      R[i] = N;
    }
    else {
      R[i] = q.top();
    }
    q.push(i);
  }
  for(int i = 0; i < N; i++) {
    if(L[i] == -1 && R[i] == N) {
      DP_Min[0][i] = -1;
      DP_Max[0][i] = -1;
    }
    else if(L[i] == -1 || R[i] == N) {
      if(L[i] == -1) {
        DP_Min[0][i] = R[i];
        DP_Max[0][i] = R[i];
      }
      else {
        DP_Min[0][i] = L[i];
        DP_Max[0][i] = L[i];
      }
    }
    else {
      if(H[L[i]] < H[R[i]]) {
        DP_Min[0][i] = L[i];
        DP_Max[0][i] = R[i];
      }
      else {
        DP_Min[0][i] = R[i];
        DP_Max[0][i] = L[i];
      }
      //DP_Min[0][i] = min(L[i], R[i]);
      //DP_Max[0][i] = max(L[i], R[i]);
    }
  }
  for(int i = 1; i < 19; i++) {
    for(int j = 0; j < N; j++) {
      if(DP_Min[i - 1][j] == -1) {
        DP_Min[i][j] = -1;
      }
      else {
        DP_Min[i][j] = DP_Min[i - 1][DP_Min[i - 1][j]];
      }
      if(DP_Max[i - 1][j] == -1) {
        DP_Max[i][j] = -1;
      }
      else {
        DP_Max[i][j] = DP_Max[i - 1][DP_Max[i - 1][j]];
      }
    }
  }
  for(int i = 0; i < N; i++) {
    if(L[i] != -1) {
      g[i].push_back(L[i]);
    }
    if(R[i] != -1) {
      g[i].push_back(R[i]);
    }
  }
}

int minimum_jumps(int A, int B, int C, int D) {
  if(okN <= 2000) {
    queue<int> q;
    vector<int> dist(MAXN, 1e9);
    for(int i = A; i <= B; i++) {
      q.push(i);
      dist[i] = 0;
    }
    while(!q.empty()) {
      int node = q.front();
      q.pop();
      for(int i = 0; i < g[node].size(); i++) {
        if(dist[g[node][i]] == 1e9) {
          dist[g[node][i]] = dist[node] + 1;
          q.push(g[node][i]);
        }
      }
    }
    int ans = 1e9;
    for(int i = C; i <= D; i++) {
      ans = min(ans, dist[i]);
    }
    if(ans == 1e9) {
      return -1;
    }
    return ans;
  }
  A++;
  B++;
  //cout << "A = " << A << ", B = " << B << ", INPUT[C] = " << INPUT[C] << "\n";
  int pos = Query(1, okN, 1, A, B, INPUT[C]).first;
  A = omk[pos];
  B = omk[pos];
  //cout << "A = " << A << ", B = " << B << "\n";
  int ans = 0, cur = B;
  for(int i = 18; i >= 0; i--) {
    if(DP_Max[i][cur] != -1 && INPUT[DP_Max[i][cur]] <= INPUT[C]) {
      //cout << "prev cur = " << cur << "\n";
      ans += (1 << i);
      cur = DP_Max[i][cur];
      //cout << "new cur = " << cur << ", with added answer: " << (1 << i) << "\n";
    }
  }
  for(int i = 18; i >= 0; i--) {
    if(DP_Min[i][cur] != -1 && INPUT[DP_Min[i][cur]] <= INPUT[C]) {
      ans += (1 << i);
      cur = DP_Min[i][cur];
    }
  }
  if(cur != C) return -1;
  return ans;
}

Compilation message (stderr)

jumps.cpp: In function 'int minimum_jumps(int, int, int, int)':
jumps.cpp:155:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  155 |       for(int i = 0; i < g[node].size(); i++) {
      |                      ~~^~~~~~~~~~~~~~~~

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