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Submission #600134

# Submission time Handle Problem Language Result Execution time Memory
600134 2022-07-20T13:30:42 Z MilosMilutinovic Dancing Elephants (IOI11_elephants) C++14
50 / 100
 6343 ms 2376 KB 
/**
 *    author:  wxhtzdy
 *    created: 20.07.2022 11:59:55
**/
#include "elephants.h"
#include <bits/stdc++.h>

using namespace std;

const int MAX = 150005;
const int BLOCK = sqrt(MAX);

int n, l, x[MAX], cnt[MAX], pos[MAX];
int id[MAX], order[MAX];

vector<int> idx[MAX / BLOCK + 5];

void BuildBlock(int i) {
  sort(idx[i].begin(), idx[i].end(), [&](int a, int b) {
    if (x[a] != x[b]) {
      return x[a] < x[b];
    } else {
      return a < b;
    }
  });
  int sz = (int) idx[i].size();
  int ptr = sz - 1;    
  for (int j = sz - 1; j >= 0; j--) {
    assert(id[idx[i][j]] == i);
    if (j + 1 < sz) {
      assert(x[idx[i][j]] <= x[idx[i][j + 1]]);
    }
    if (x[idx[i][sz - 1]] - x[idx[i][j]] <= l) {
      cnt[idx[i][j]] = 1;
      pos[idx[i][j]] = x[idx[i][j]] + l;
    } else { 
      while (x[idx[i][ptr]] - x[idx[i][j]] > l) {
        ptr -= 1;
      }
      cnt[idx[i][j]] = cnt[idx[i][ptr + 1]] + 1;
      pos[idx[i][j]] = pos[idx[i][ptr + 1]];
    }                              
  }
}

void Build() {     
  for (int i = 0; i < n; i++) {
    order[i] = i;
  }
  sort(order, order + n, [&](int i, int j) {
    if (x[i] != x[j]) {
      return x[i] < x[j];
    } else {
      return i < j;
    }
  });
  for (int i = 0; i <= n / BLOCK; i++) {
    idx[i].clear();
  }
  for (int i = 0; i < n; i++) {
    id[order[i]] = i / BLOCK;
    idx[id[order[i]]].push_back(order[i]);
  }
  for (int i = 0; i <= n / BLOCK; i++) {
    BuildBlock(i);
  }
}

int Q;

bool first = true;

int update(int i, int y) {
  ++Q;
  x[i] = y;
  if (Q == BLOCK / 7) {
    Build();
    Q = 0;
    int lst = -1;       
    for (int j = 0; j <= n / BLOCK; j++) {
      if (idx[j].empty()) {
        continue;
      }
      assert(lst <= x[idx[j][0]]);
      lst = x[idx[j].back()];
    }
  } else {
    vector<int> b;
    bool found = false;
    for (int j = 0; j < (int) idx[id[i]].size(); j++) {
      if (idx[id[i]][j] != i) {      
        b.push_back(idx[id[i]][j]);
      } else {
        found = true;
      }
    }
    assert(found);                      
    idx[id[i]] = b;
    BuildBlock(id[i]);
    b.clear();
    int lst = -1;       
    for (int j = 0; j <= n / BLOCK; j++) {
      if (idx[j].empty()) {
        continue;
      }
      assert(lst <= x[idx[j][0]]);
      lst = x[idx[j].back()];
    }
    for (int j = n / BLOCK; j >= 0; j--) {
      if (!idx[j].empty() && x[idx[j][0]] <= x[i]) {
        id[i] = j;
        break;
      } 
    }        
    idx[id[i]].push_back(i);
    /*if (idx[id[i]].empty() || x[idx[id[i]].back()] < y) {
    } else {
      vector<int> b;    
      for (int j = 0; j < (int) idx[id[i]].size(); j++) {
        if (y <= x[idx[id[i]][j]]) {
          b.push_back(i);
          y = (int) 1.01e9;
          j -= 1;
        } else {
          b.push_back(idx[id[i]][j]);
        }
      }
      idx[id[i]] = b;
    }*/
    BuildBlock(id[i]);
  } 
  //Build(); // brute force check
  int ans = 0, R = -1;
  for (int j = 0; j <= n / BLOCK; j++) {
    if (idx[j].empty() || x[idx[j].back()] <= R) {
      continue;
    }                                          
    int low = 0, high = (int) idx[j].size() - 1, at = 0;
    while (low <= high) {
      int mid = low + high >> 1;
      if (x[idx[j][mid]] > R) {
        at = mid;
        high = mid - 1;
      } else {
        low = mid + 1;
      }
    }
    assert(R < x[idx[j][at]] && (at == 0 || R >= x[idx[j][at - 1]]));
    ans += cnt[idx[j][at]];
    R = pos[idx[j][at]];
  }
  if (false) {
    for (int i = 0; i < n; i++) {
      order[i] = i;
    }
    sort(order, order + n, [&](int i, int j) {
      return x[i] < x[j];
    });     
    int nans = 0;
    for (int i = 0; i < n; i++) {
      int ptr = i;
      while (ptr + 1 < n && x[order[ptr + 1]] <= x[order[i]] + l) {
        ptr += 1;
      }
      i = ptr;
      nans += 1;
    }
    assert(nans == ans);
    first = false;
  }  
  return ans; 
}

void init(int N, int L, int* X) {
  n = N;
  l = L;
  for (int i = 0; i < n; i++) {
    x[i] = X[i];
  }
  Build();
  int lst = -1;       
  for (int j = 0; j <= n / BLOCK; j++) {
    if (idx[j].empty()) {
      continue;
    }
    assert(lst <= x[idx[j][0]]);
    lst = x[idx[j].back()];
  }
}

Compilation message

elephants.cpp: In function 'int update(int, int)':
elephants.cpp:140:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  140 |       int mid = low + high >> 1;
      |                 ~~~~^~~~~~

Subtask #1
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 0 ms 340 KB Output is correct

Subtask #2
16.0 / 16.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 0 ms 340 KB Output is correct
4 Correct 1 ms 340 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 0 ms 340 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 0 ms 340 KB Output is correct
4 Correct 1 ms 340 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 0 ms 340 KB Output is correct
7 Correct 1702 ms 1288 KB Output is correct
8 Correct 1905 ms 1432 KB Output is correct
9 Correct 3301 ms 2360 KB Output is correct
10 Correct 3766 ms 2376 KB Output is correct
11 Correct 3553 ms 2356 KB Output is correct
12 Correct 6343 ms 2360 KB Output is correct
13 Correct 3554 ms 2360 KB Output is correct

Subtask #4
0 / 47.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 0 ms 340 KB Output is correct
4 Correct 1 ms 340 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 0 ms 340 KB Output is correct
7 Correct 1702 ms 1288 KB Output is correct
8 Correct 1905 ms 1432 KB Output is correct
9 Correct 3301 ms 2360 KB Output is correct
10 Correct 3766 ms 2376 KB Output is correct
11 Correct 3553 ms 2356 KB Output is correct
12 Correct 6343 ms 2360 KB Output is correct
13 Correct 3554 ms 2360 KB Output is correct
14 Incorrect 2639 ms 1668 KB Output isn't correct
15 Halted 0 ms 0 KB -

Subtask #5
0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 0 ms 340 KB Output is correct
4 Correct 1 ms 340 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 0 ms 340 KB Output is correct
7 Correct 1702 ms 1288 KB Output is correct
8 Correct 1905 ms 1432 KB Output is correct
9 Correct 3301 ms 2360 KB Output is correct
10 Correct 3766 ms 2376 KB Output is correct
11 Correct 3553 ms 2356 KB Output is correct
12 Correct 6343 ms 2360 KB Output is correct
13 Correct 3554 ms 2360 KB Output is correct
14 Incorrect 2639 ms 1668 KB Output isn't correct
15 Halted 0 ms 0 KB -