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  1. #include <ctime>
  2. #include <algorithm>
  3. #include <random>
  4. #include <iostream>
  5. #include <set>
  6.  
  7. double boundedSumJoe(std::vector<int> x, int lower, int upper) {
  8.  
  9.     int myMax = *std::max_element(x.begin(), x.end());
  10.     int offSet = std::abs(*std::min_element(x.begin(), x.end())) + 1;
  11.     unsigned long int myRange;
  12.  
  13.     if (myMax > 0)
  14.         myRange = myMax + offSet;  // E.g. if myMax = 10 & myMin = -2, then myRange = 12
  15.     else
  16.         myRange = offSet;
  17.  
  18.     offSet--;
  19.  
  20.     std::vector<int> frequency(myRange, 0);
  21.     std::vector<int> values(myRange, 0);
  22.     std::vector<int>::iterator it, itEnd = x.end();
  23.     int myIndex;
  24.     double mySum = 0;
  25.  
  26.     for (it = x.begin(); it < itEnd; it++) {
  27.         myIndex = *it + offSet;
  28.         frequency[myIndex]++;
  29.         values[myIndex] = *it;
  30.     }
  31.  
  32.     int count = 0;
  33.     bool firstHit = true;
  34.  
  35.     for (std::size_t j = 0; j < myRange; j++) {
  36.         if (frequency[j]) {
  37.             if (count >= lower) {
  38.                 if (count <= upper) {
  39.                     firstHit = false;
  40.                     mySum += values[j] * frequency[j];
  41.                 } else {
  42.                     if ((count - upper) > 1) {
  43.                         int k = j - 1;
  44.                         while (!frequency[k]) {k--;}
  45.                         mySum -= (values[k] * (count - upper - 1));
  46.                     }
  47.                     break;
  48.                 }
  49.             }
  50.             count += frequency[j];
  51.             if ((count - lower) >= 1 && firstHit) {
  52.                 firstHit = false;
  53.                 mySum += (values[j] * (count - lower));
  54.             }
  55.         }
  56.     }
  57.  
  58.     return mySum;
  59. }
  60.  
  61. double boundedSumBen(std::vector<int> x, int lower, int upper) {
  62.     double mySum = 0;
  63.     // First partition vector at larger bound
  64.     std::nth_element(x.begin(), x.begin() + upper, x.end());
  65.     // Now create partition of above at lower bound
  66.     std::nth_element(x.begin(), x.begin() + lower, x.begin() + upper);
  67.     std::vector<int>::iterator it, itEnd = x.begin() + upper;
  68.     for (it = x.begin() + lower; it <= itEnd; it++)
  69.         mySum += *it;
  70.     return mySum;
  71. }
  72.  
  73. double boundedSumOP(std::vector<int> x, int lower, int upper) {
  74.     double mySum = 0;
  75.     std::sort(x.begin(), x.end());
  76.     std::vector<int>::iterator it, itEnd = x.begin() + upper;
  77.     for (it = x.begin() + lower; it <= itEnd; it++)
  78.         mySum += *it;
  79.     return mySum;
  80. }
  81.  
  82. int main() {
  83.     std::vector<int> v(200001);
  84.     std::random_device rd;
  85.     std::mt19937 gen(rd());
  86.     std::iota(v.begin(), v.end(), -100000);
  87.     std::shuffle(v.begin(), v.end(), gen);
  88.  
  89.     // random-sample without replacement
  90.     std::vector<int> randVec(v.begin(), v.begin() + 100000);
  91.     int val1, val2, val3;
  92.     std::clock_t start_time, end_time;
  93.  
  94.     start_time = clock();
  95.     for (std::size_t i = 0; i < 100; i++)
  96.         val1 = boundedSumBen(randVec, 49900, 50100);
  97.     end_time = clock();
  98.  
  99.     std::cout << "time taken on sample w/o rep std::nth_element : " <<
  100.         end_time - start_time << std::endl;
  101.  
  102.     start_time = clock();
  103.     for (std::size_t i = 0; i < 100; i++)
  104.         val2 = boundedSumJoe(randVec, 49900, 50100);
  105.     end_time = clock();
  106.  
  107.     std::cout << "time taken on sample w/o rep indexing method by Joe : " <<
  108.         end_time - start_time << std::endl;
  109.  
  110.     start_time = clock();
  111.     for (std::size_t i = 0; i < 100; i++)
  112.         val3 = boundedSumOP(randVec, 49900, 50100);
  113.     end_time = clock();
  114.  
  115.     std::cout << "time taken on sample w/o rep naive approach with std::sort : " <<
  116.         end_time - start_time << std::endl;
  117.  
  118.     std::cout << "All functions on sample w/o rep return the same value of : " <<
  119.         val1 << ", " << val2 << ", and " << val3 << std::endl;
  120.  
  121.  
  122.     /// Now we test a random sample with replacement
  123.     std::uniform_int_distribution<int> distribution(-100000, 100000);
  124.     for (std::size_t i = 0; i < 100000; i++)
  125.         randVec[i] = distribution(gen);
  126.  
  127.     start_time = clock();
  128.     for (std::size_t i = 0; i < 100; i++)
  129.         val1 = boundedSumBen(randVec, 9900, 10100);
  130.     end_time = clock();
  131.  
  132.     std::cout << "time taken on sample with rep std::nth_element : " <<
  133.         end_time - start_time << std::endl;
  134.  
  135.     start_time = clock();
  136.     for (std::size_t i = 0; i < 100; i++)
  137.         val2 = boundedSumJoe(randVec, 9900, 10100);
  138.     end_time = clock();
  139.  
  140.     std::cout << "time taken on sample with rep indexing method by Joe : " <<
  141.         end_time - start_time << std::endl;
  142.  
  143.     start_time = clock();
  144.     for (std::size_t i = 0; i < 100; i++)
  145.         val3 = boundedSumOP(randVec, 9900, 10100);
  146.     end_time = clock();
  147.  
  148.     std::cout << "time taken on sample with rep naive approach with std::sort : " <<
  149.         end_time - start_time << std::endl;
  150.  
  151.     std::cout << "All functions on sample with rep return the same value of : " <<
  152.         val1 << ", " << val2 << ", and " << val3 << std::endl;
  153.  
  154.     std::cout << "Number of unique elements in vector with replacement "
  155.              << std::set<int>(randVec.begin(), randVec.end()).size()
  156.              << std::endl;
  157.  
  158.     return 0;
  159. }
  160.  
Success #stdin #stdout 1.53s 7820KB
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stdin
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Standard input is empty
stdout
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time taken on sample w/o rep std::nth_element : 81165
time taken on sample w/o rep indexing method by Joe : 170489
time taken on sample w/o rep naive approach with std::sort : 504257
All functions on sample w/o rep return the same value of : 276, 276, and 276
time taken on sample with rep std::nth_element : 82159
time taken on sample with rep indexing method by Joe : 151076
time taken on sample with rep naive approach with std::sort : 508046
All functions on sample with rep return the same value of : -16071322, -16071322, and -16071322
Number of unique elements in vector with replacement 78658
https://ideone.com/rl53Ly
language:
C++ (gcc 8.3)
created:
6 years ago
visibility:
public

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