Posted on 16 Aug 2022, this text provides information on QA/Testing related to General Tech. Please note that while accuracy is prioritized, the data presented might not be entirely correct or up-to-date. This information is offered for general knowledge and informational purposes only, and should not be considered as a substitute for professional advice.
Here is a piece of C++ code that seems very peculiar. For some strange reason, sorting the data miraculously makes the code almost six times faster.
#include#include#includeintmain(){// Generate dataconstunsigned arraySize =32768;int data[arraySize];for(unsigned c =0; c < arraySize;++c)
data[c]= std::rand()%256;// !!! With this, the next loop runs faster
std::sort(data, data + arraySize);// Testclock_t start = clock();longlong sum =0;for(unsigned i =0; i <100000;++i){// Primary loopfor(unsigned c =0; c < arraySize;++c){if(data[c]>=128)
sum += data[c];}}double elapsedTime =static_cast(clock()- start)/ CLOCKS_PER_SEC;
std::cout << elapsedTime << std::endl;
std::cout <<"sum = "<< sum << std::endl;}
Without std::sort(data, data + arraySize);, the code runs in 11.54 seconds.
With the sorted data, the code runs in 1.93 seconds.
Initially, I thought this might be just a language or compiler anomaly. So I tried it in Java.
import java.util.Arrays;import java.util.Random;publicclassMain{publicstaticvoidmain(String[] args){// Generate dataint arraySize =32768;int data[]=newint[arraySize];Random rnd =newRandom(0);for(int c =0; c < arraySize;++c)
data
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manpreet
Best Answer
2 years ago
Here is a piece of C++ code that seems very peculiar. For some strange reason, sorting the data miraculously makes the code almost six times faster.
std::sort(data, data + arraySize);
, the code runs in 11.54 seconds.Initially, I thought this might be just a language or compiler anomaly. So I tried it in Java.