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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. using namespace std;
  5.  
  6. const int N = (int)20;
  7.  
  8. int a[N];
  9.  
  10. void merge(int start, vector<int> v1, vector<int> v2) {
  11.   int i = 0, j = 0;
  12.  
  13.   while(i < v1.size() && j < v2.size()) {
  14.     if (v1[i] <= v2[j]) a[start++] = v1[i++];
  15.     else a[start++] = v2[j++];
  16.   }
  17.  
  18.   while(i < v1.size()) a[start++] = v1[i++];
  19.   while(j < v2.size()) a[start++] = v2[j++];
  20. }
  21.  
  22. void merge_sort(int left, int right) {
  23.   if (left >= right) return;
  24.  
  25.   int mid = (left + right) / 2;
  26.  
  27.   vector<int> l, r;
  28.  
  29.   merge_sort(left, mid);
  30.   merge_sort(mid + 1, right);
  31.  
  32.   for(int i = left; i <= mid; i++) l.push_back(a[i]);
  33.   for(int i = mid+1; i <= right; i++) r.push_back(a[i]);
  34.  
  35.   merge(left, l, r);
  36. }
  37.  
  38. bool is_sorted() {
  39.   for(int i = 0; i < N - 1; i++) if (a[i] > a[i + 1]) return false;
  40.   return true;
  41. }
  42.  
  43. int main() {
  44.   for(int i =0 ; i < N; i++) a[i] = rand() % 1001;
  45.  
  46.   merge_sort(0, N - 1);
  47.  
  48.   cout << "sorted: " << is_sorted() << endl;
  49. }
  50.  
Success #stdin #stdout 0.01s 5272KB
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stdin
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Standard input is empty
stdout
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sorted: 1
https://ideone.com/65s8m6
language:
C++14 (clang 8.0)
created:
7 days ago
visibility:
public

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