10000000 in 1

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doit.cpp

#include <stdio.h>
#include <vector>
#include <sstream>
#include <fstream>
#include <string>
#include <chrono>


unsigned int count_prime(int prime, int n) {
    unsigned int ret = 0;
    unsigned int temp = n/prime;
    while(temp != 0) {
        ret += temp;
        temp /= prime;
    }
    return ret;
}

bool is_prime(int num) {
    if (num <= 3) {
        return num >= 2;
    }
    if (num%2==0 || num%3==0) {
        return false;
    }
    for (int i = 5; i*i<=num; i+=6) {
        if (num%i==0 || num%(i+2)==0) {
            return false;
        }
    }
    return true;
}


void show_message(std::vector<std::pair<int, unsigned int> > &data, bool showtoscreen, bool savetofile) {
    std::stringstream ss;
    ss << "{";

    for (auto iter = data.begin(); iter != data.end(); ++iter) {
        ss << iter->first << ": " << iter->second << ", ";
    }

    std::string message = ss.str();
    if (!data.empty()) {
        message.pop_back();
        message.pop_back();
    }
    message.push_back('}');
    if (savetofile) {
        std::ofstream fout("./temp_message.txt", std::ios_base::out);
        fout.write(message.c_str(), message.size());
        fout.close();
    }
    if (showtoscreen) {
        printf("%s\n", message.c_str());
    }
    return void();
}


void go(int n, std::vector<std::pair<int, unsigned int> > &ret) {

    auto t0 = std::chrono::high_resolution_clock::now();
    for (int i = 2; i <= n; ++i) {
        if (is_prime(i)) {
            unsigned int count_num = count_prime(i, n);
            ret.push_back(std::make_pair(i, count_num));
        }
    }
    auto t1 = std::chrono::high_resolution_clock::now();

    int64_t nanosecond = std::chrono::duration_cast<std::chrono::nanoseconds>(t1 - t0).count();


    printf("time:%0.6fs\n", nanosecond*1.0/1e9);
}


bool is_prime(int num, std::vector<std::pair<int, unsigned int> >&refer) {
    if (num <= 3) {
        return num >= 2;
    }
    for (auto iter = refer.begin(); iter != refer.end(); ++iter) {
        if (num%iter->first == 0) {
            return false;
        }
    }
    return true;
}

void go2(int n, std::vector<std::pair<int, unsigned int> > &ret) {
    auto t0 = std::chrono::high_resolution_clock::now();

    for (int i = 2; i <= n; ++i) {
        if (is_prime(i, ret)) {
            unsigned int count_num = count_prime(i, n);
            ret.push_back(std::make_pair(i, count_num));
        }
    }
    auto t1 = std::chrono::high_resolution_clock::now();

    int64_t nanosecond = std::chrono::duration_cast<std::chrono::nanoseconds>(t1 - t0).count();


    printf("time:%0.6fs\n", nanosecond*1.0/1e9);

}

int main(int argc, char **argv) {
    if (argc < 2) {
        printf("please input the max num\n");
        return 0;
    }

    int n = strtol(argv[1], NULL, 10);

    std::vector<std::pair<int, unsigned int> > ret;
    go(n, ret);
    show_message(ret, n <= 500, n <= 1000000);
    return 0;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.5)
project(doit)
set (lib_name doit)
add_executable(${lib_name} doit.cpp)

countprime.py

#coding=utf-8
import sys
import time
import getopt



def is_prime(value):
    if value <= 3:
        return value >= 2
    if value%2 == 0 or value%3 == 0:
        return False

    i = 5
    while i*i <= value:
        if value%i == 0 or value%(i+2) == 0:
            return False
        i += 6
    return True

def count_prime(n, prime):
    ret = 0
    temp = n/prime
    while not temp == 0:
        ret += temp
        temp /= prime
    return ret


def go(n):
    li = []
    for i in range(2, n+1):
        if is_prime(i):
            count = count_prime(n, i)
            pair = (i, count)
            li.append(pair)
    return li



def main(argv):
    if len(argv) >= 2:
        n = int(argv[1])
        t1 = time.clock()
        li = go(n)
        # time.sleep(1000)
        t2 = time.clock()
        if (n < 500):
            print li
        print"spend time:",t2-t1
    else:
        print "please input the argument"

if __name__ == '__main__':
    main(sys.argv)