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  1. #pragma GCC optimize("O2")
  2. #include <bits/stdc++.h>
  3.  
  4. using namespace std;
  5.  
  6. struct timeit {
  7.     decltype(chrono::high_resolution_clock::now()) begin;
  8.     const string label;
  9.     timeit(string label = "???") : label(label) { begin = chrono::high_resolution_clock::now(); }
  10.     ~timeit() {
  11.         auto end = chrono::high_resolution_clock::now();
  12.         auto duration = chrono::duration_cast<chrono::milliseconds>(end - begin).count();
  13.         cerr << duration << "ms elapsed [" << label << "]" << endl;
  14.     }
  15. };
  16. const int MAXN = 1e6 + 5;
  17. const int ITERS = 100;
  18. signed main() {
  19.     ios::sync_with_stdio(0);
  20.     cin.tie(0);
  21.     vector<int> vc(MAXN);
  22.     {
  23.         timeit t("vector char memset");
  24.         for (int t = 0; t < ITERS; t++)
  25.         	fill(vc.begin(), vc.end(),0);
  26.     }
  27.     {
  28.         timeit t("vector char loop");
  29.         for (int t = 0; t < ITERS; t++)
  30.             for (auto &i : vc)
  31.                 i = 0;
  32.     }
  33. }
Success #stdin #stdout #stderr 0.06s 15240KB
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stdin
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Standard input is empty
stdout
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Standard output is empty
stderr
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33ms elapsed [vector char memset]
30ms elapsed [vector char loop]
https://ideone.com/zF1YWY
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
public

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