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  1. #include <iostream>
  2. #include <vector>
  3. #include <algorithm>
  4. #include <cassert>
  5.  
  6. struct DataStruct {
  7.     std::vector<int> arr, add;
  8.  
  9.     const int GSIZE = 128;
  10.  
  11.     DataStruct(int size, int value) {
  12.         arr.assign(size, value);
  13.         add.assign(size / GSIZE + 1, 0);
  14.     }
  15.  
  16.     void push(int g) {
  17.         if (add[g] == 0) {
  18.             return;
  19.         }
  20.         const int begin = GSIZE * g;
  21.         const int after = std::min(begin + GSIZE, (int)arr.size());
  22.         int a = add[g];
  23.         for (int i = begin; i < after; ++i) {
  24.             arr[i] += a;
  25.         }
  26.         add[g] = 0;
  27.     }
  28.  
  29.     void push_all() {
  30.         for (int g = 0; g < (int)add.size(); ++g) {
  31.             push(g);
  32.         }
  33.     }
  34.  
  35.     void inc(int left, int right) {
  36.         assert(right < (int)arr.size());
  37.         int gl = left / GSIZE;
  38.         int gr = right / GSIZE;
  39.         if (gl == gr) {
  40.             push(gl);
  41.             for (int i = left; i <= right; ++i) {
  42.                 arr[i]++;
  43.             }
  44.         } else {
  45.             push(gl);
  46.             push(gr);
  47.             for (int i = left, after = (gl+1) * GSIZE; i < after; ++i) {
  48.                 arr[i]++;
  49.             }
  50.             for (int g = gl+1; g < gr; ++g) {
  51.                 add[g]++;
  52.             }
  53.             for (int i = gr * GSIZE; i <= right; ++i) {
  54.                 arr[i]++;
  55.             }
  56.         }
  57.     }
  58. };
  59.  
  60.  
  61. int main() {
  62.     std::ios_base::sync_with_stdio(false);
  63.     std::cin.tie(0); std::cout.tie(0); std::cerr.tie(0);
  64.  
  65.     int n, last;
  66.     std::cin >> n >> last;
  67.  
  68.     DataStruct ds(last+1, 0);
  69.  
  70.     for (int i = 0; i < n; ++i) {
  71.         int x, p; std::cin >> x >> p;
  72.         int l = std::max(0, x-p);
  73.         int r = std::min(last, x+p);
  74.         ds.inc(l, r);
  75.     }
  76.     ds.push_all();
  77.     for (auto& it : ds.arr) if (it > 1) it = 0;
  78.     int answ = 0;
  79.     for (int i = 0; i <= last;) {
  80.         while (i <= last && ds.arr[i] == 1) ++i;
  81.         if (i > last) break;
  82.         int j = i;
  83.         while (j <= last && ds.arr[j] == 0) ++j;
  84.         answ = std::max(answ, j-i);
  85.         i = j;
  86.     }
  87.     std::cout << answ;
  88.     return 0;
  89. }
Success #stdin #stdout 0s 4364KB
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https://ideone.com/lBii00
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
public

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