//第三部分、提取出某日访问百度次数最多的那个IP

#include <iostream>

#include <fstream>

#include <ctime>

using namespace std;

#define N 32

#define ID(x) (x >> 27)

#define VALUE(x) (x&0x07ffffff)

#define MAKE_IP(x,y) ((x<<27)|y)

#define MEM_SIZE 128*1024*1024

void make_data(const int& n, char *data_path)

{

ofstream out(data_path, ios::out|ios::binary);

srand((unsigned int)time(NULL));

if (out)

{

for (int i = 0; i < n; ++i)

{

unsigned val = (unsigned)rand();

val = val<<24|val;

out.write((char *)&val, sizeof(unsigned));

}

}

}

void FindMaxIP(const char *pcFile)

{

fstream arr[N];

char tmp_path[256];

for (int i = 0; i < N; ++i)

{

sprintf_s(tmp_path, "E:/test/tmp%d.dat", i);

arr[i].open(tmp_path, ios::trunc|ios::in|ios::out|ios::binary);

if (!arr[i]) cout << "open file " << i << "error" << endl;

}

ifstream infile(pcFile, ios::in|ios::binary);

unsigned data;

while (infile.read((char *)(&data), sizeof(data)))

{

unsigned val = VALUE(data);

int key = ID(data);

arr[key].write((char*)(&val), sizeof(val));

}

for (unsigned i = 0; i < N; ++i) arr[i].seekg(0);

unsigned max_ip = 0, max_times = 0;

unsigned *count = new unsigned[MEM_SIZE];

for (unsigned i = 0; i < N; ++i)

{

memset(count, 0, sizeof(unsigned)*MEM_SIZE);

unsigned data;

while (arr[i].read((char *)(&data), sizeof(unsigned))) ++count[data];

for (unsigned j = 0; j < MEM_SIZE; ++j)

{

if (max_times < count[j])

{

max_times = count[j];

max_ip = MAKE_IP(i, j);

}

}

}

delete[] count;

unsigned char *result = (unsigned char *)(&max_ip);

printf("出现次数最多的IP为:%d.%d.%d.%d , 出现%d次\n",

result[0], result[1], result[2], result[3], max_times);

}

int main(void)

{

char acIPFile[] = "E:\\test\\ip.dat";

make_data(100000000, acIPFile);

FindMaxIP(acIPFile);

return 0;

}