Submission #654722

#	Time	Username	Problem	Language	Result	Execution time	Memory
654722		Sam_a17	Rainforest Jumps (APIO21_jumps)	C++14	56 / 100	4048 ms	58096 KiB

jumps

#include <bits/stdc++.h>
using namespace std;
 
#define dbg(x) cerr << #x << " " << x << endl;
 
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<int> tree;
  int size = 1;

  void init(int s) {
    while(size < s) {
      size *= 2;
    }
    tree.assign(2 * size - 1, 0);
  }

  void upd(int u, int val, int x, int lx, int rx) {
    if(rx - lx == 1) {
      // dbg(val)
      tree[x] = val;
      return;
    }

    int mid = (lx + rx) / 2;
    if(u < mid) {
      upd(u, val, 2 * x + 1, lx, mid);
    } else {
      upd(u, val, 2 * x + 2, mid, rx);
    }

    tree[x] = max(tree[2 * x + 1], tree[2 * x + 2]);
  }
  
  void upd(int u, int val) {
    upd(u, val, 0, 0, size);
  }

  int qry(int l, int r, int x, int lx, int rx) {
    if(lx >= r || rx <= l) {
      return 0;
    }

    if(lx >= l && rx <= r) {
      return tree[x];
    }

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

  int 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) {
  if(A == B && C == D) {
    int maxim = seg.qry(A, D);
    if(maxim >= h[D]) {
      return -1;
    }

    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) {
        answ = mid;
        inb = mid - 1;
      } else {
        ina = mid + 1;
      }
    }

    int pos = get_mx(answ, A);
    if(pos == D) return answ;
    if(h[pos] >= h[D]) { 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(h[pos2] >= h[D]) {
        answ2 = mid;
        inb = mid - 1;
      } else {
        ina = mid + 1;
      }
    }

    pos = get_r(answ2, pos);
    return answ2 + answ;
  } else {
    queue<pair<int, int>> q;
    vector<bool> vis(n + 1);
    for(int i = A; i <= B; i++) {
      q.push({i, 0});
      vis[i] = true;
    }
  
    while(!q.empty()) {
      auto u = q.front();
      q.pop();
  
      if(u.first >= C && u.first <= D) {
        return u.second;
      }
  
      if(nxt[u.first][0] != -1 && !vis[nxt[u.first][0]]) {
        vis[nxt[u.first][0]] = true;
        q.push({nxt[u.first][0], u.second + 1});
      }
  
      if(pre[u.first][0] != -1 && !vis[pre[u.first][0]]) {
        vis[pre[u.first][0]] = true;
        q.push({pre[u.first][0], u.second + 1});
      }
    }
  
    return -1;
  }
}

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