Add program and README

.gitignore

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+cmake-build-debug
+primes.txt
+main

.idea/.gitignore

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+# Default ignored files
+/workspace.xml

.idea/.name

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+c___primes

.idea/c++-primes.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module classpath="CMake" type="CPP_MODULE" version="4" />

.idea/discord.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="DiscordProjectSettings">
+    <option name="show" value="true" />
+  </component>
+  <component name="ProjectNotificationSettings">
+    <option name="askShowProject" value="false" />
+  </component>
+</project>

.idea/misc.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="CMakeWorkspace" PROJECT_DIR="$PROJECT_DIR$" />
+  <component name="JavaScriptSettings">
+    <option name="languageLevel" value="ES6" />
+  </component>
+</project>

.idea/modules.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/.idea/c++-primes.iml" filepath="$PROJECT_DIR$/.idea/c++-primes.iml" />
+    </modules>
+  </component>
+</project>

.idea/vcs.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>

CMakeLists.txt

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+cmake_minimum_required(VERSION 3.15)
+project(c___primes)
+
+set(CMAKE_CXX_STANDARD 20)
+
+add_executable(c___primes main.cpp)

README.md

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-c++-primes
+# Primes in c++
+
+## Usage
+
+```bash
+# build
+g++ -lpthread -o main main.cpp
+
+# run
+./main
+```

main.cpp

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+#include <iostream>
+#include <pthread.h>
+#include <tuple>
+#include <thread>
+
+using namespace std;
+using std::cout;
+
+uint numThreads;
+
+void *GetPrimes(void* start) {
+    ulong num = (ulong) start;
+    ulong incr = numThreads * 2;
+    while (true) {
+        bool  isPrime = true;
+        if (num < 3 || num % 2 == 0) {
+            num += incr;
+            continue;
+        }
+        for (int i = 3; i < num/2; i += 2) {
+            if (num % i == 0) {
+                isPrime = false;
+                break;
+            }
+        }
+        if (isPrime) {
+            cout << num << "\n";
+        }
+        num += incr;
+    }
+}
+
+int main() {
+    numThreads = thread::hardware_concurrency();
+    pthread_t threads[numThreads];
+    long start = 1;
+    int rc;
+    for (int i = 0; i < numThreads; i++) {
+        rc = pthread_create(&threads[i], NULL, GetPrimes, (void *)(start + (2*i)));
+        if (rc) {
+            cout << "Error";
+            exit(-1);
+        }
+    }
+    pthread_exit(NULL);
+}
+