제출 #600123

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
600123		MilosMilutinovic	코끼리 (Dancing Elephants) (IOI11_elephants)	C++14	50 / 100	5699 ms	3208 KiB

elephants

/**
 *    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;
  } 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();
    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]);
  } 
  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()];
  }
  //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();
}

컴파일 시 표준 에러 (stderr) 메시지

elephants.cpp: In function 'int update(int, int)':
elephants.cpp:132:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  132 |       int mid = low + high >> 1;
      |                 ~~~~^~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 16 / 16
• Subtask 3: 24 / 24
• Subtask 4: 0 / 47
• Subtask 5: 0 / 3