百度筆試題：
ip地址存在文件中，例如10.0.0.1 10.0.0.10,一共有n行，文件小於2k，表示爲ip地址的一個範圍（也就是說前一個小，後一個大）
例如:
10.0.0.1 10.0.0.10
10.0.0.4 10.0.0.8
10.0.0.6 10.0.0.15
10.0.0.23 10.0.0.123
輸出爲： 10.0.0.1 10.0.0.123
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//// baidu Corp. ///////// 2007.10.22 Paper Test in Nanjing. //////
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#include <iostream>#include <fstream>#include <sstream>#include <ctime>#include <vector>using namespace std;//we can also definie a class, then overload operator '>' and '<' to solve this problem.//And maybe use this method, have a kind of oo thinking.typedef struct tagip{ int a; int b; int c; int d;}_ip;/**func: open file*parameter1: file stream [in]*parameter2: file name*return: file stream [out]*/fstream & open_file( fstream & s, const string & file ){ s.close(); s.clear(); s.open( file.c_str(), fstream::in ); return s;}/**func: check the first num is less than the second one*parameter1: the first nums a[0].a[1].a[2].a[3]*parameter2: get the value required to check*parameter3: the num of checking*return ...*/int check_num( int a[], int& value, int i ){ if( a[i] > value ) return 1; if( a[i] == value ) return 0; return -1;}/**func: produce ip.txt*similar as:*10.0.0.0 10.0.0.1*problem: cannot control the first number is less than the second one*/void produce_ip_file( const string& filename ){ fstream file; file.open( filename.c_str(), fstream::out ); srand( ( unsigned int )time( NULL ) ); //seed int i, j, value; int a[4]; //a[0].a[1].a[2].a[3] int index; string str_ip; for( i = 0; i < 40; i++ )
{
ostringstream stream_string; //format input value index = 0; for( j = 0; j < 8; j++ ) { if( j < 4 ) { a[j] = rand() % 255; stream_string << a[j];
} else { if( index == 0 ) { do { value = rand() % 255; }while( ( index = check_num( a, value, j-4 ) ) == 1 ); stream_string << value; } else if( index == -1 ) { stream_string << rand() % 255; } } if( j != 3 && j != 7) { stream_string << "."; } else if( j != 7 ) { stream_string << " "; } } stream_string << " "; file << stream_string.str(); } file.close(); file.clear();}/**func: read ip from file, and decompose these data to structure*parameter1: filename*parameter2: this first ip-address is decomposed into struct*parameter3: this second ip-address is decomposed into struct*/void read_file( const string& filename, vector< _ip * >& vec_ip1, vector< _ip* >& vec_ip2 ){ fstream file; if( !open_file( file, filename ) ) { cout << "cannot open " << filename << endl; return ; } int a1,b1,c1,d1; int a2,b2,c2,d2; string line; char c; while( getline( file, line ) ) { istringstream stream(line); stream >> a1 >> c >> b1 >> c >> c1 >> c >> d1 >> a2 >> c >> b2 >> c >> c2 >> c >> d2; _ip * _p1 = new _ip; _p1 -> a = a1; _p1 -> b = b1; _p1 -> c = c1; _p1 -> d = d1; vec_ip1.push_back( _p1 ); _ip * _p2 = new _ip; _p2 -> a = a2; _p2 -> b = b2; _p2 -> c = c2; _p2 -> d = d2; vec_ip2.push_back( _p2 ); }}/**func: get the minimun of the first ip-address and the maximun of the second ip-address --range*parameter1: this first ip-address is decomposed into struct*parameter2: this second ip-address is decomposed into struct*parameter3: the index of minimun*parameter4: the index of maximun*/void get_range( vector< _ip * >& vec_ip1, vector< _ip* >& vec_ip2, int& min, int& max ){ min = 0; max = 0; int i = 1; vector< _ip* >::const_iterator iter = vec_ip1.begin(); _ip * _min = *iter; ++iter; while( iter != vec_ip1.end() ) { if( _min -> a > (*iter) -> a ) { _min = *iter; min = i; } else if( _min -> a == (*iter) -> a ) { if( _min -> b > (*iter) -> b ) { _min = *iter; min = i; } else if( _min -> b == (*iter) -> b ) { if( _min -> c > (*iter) -> c ) { _min = *iter; min = i; } else if( _min -> c == (*iter) -> c ) { if( _min -> d > (*iter) -> d ) { _min = *iter; min = i; } } } } ++i; ++iter; } iter = vec_ip2.begin(); _ip * _max = *iter; ++iter; i = 1; while( iter != vec_ip2.end() ) { if( _max -> a < (*iter) -> a ) { _max = *iter; max = i; } else if( _max -> a == (*iter) -> a ) { if( _max -> b < (*iter) -> b ) { _max = *iter; max = i; } else if( _max -> b == (*iter) -> b ) { if( _max -> c < (*iter) -> c ) { _max = *iter; max = i; } else if( _max -> c == (*iter) -> c ) { if( _max -> d < (*iter) -> d ) { _max = *iter; max = i; } } } } ++i; ++iter; } }int main( int argc, char **argv ){ const string filename("ip.txt"); produce_ip_file( filename ); vector< _ip * > vec_ip1; vector< _ip * > vec_ip2; read_file( filename, vec_ip1, vec_ip2 ); int min, max; get_range( vec_ip1, vec_ip2, min, max ); cout << vec_ip1[min]->a << "." << vec_ip1[min]->b << "." << vec_ip1[min]->c << "." <<vec_ip1[min]->d << " " << vec_ip2[max]->a << "." << vec_ip2[max]->b << "." << vec_ip2[max]->c << "." <<vec_ip2[max]->d << endl; vector< _ip* >::iterator iter = vec_ip1.begin(); while( iter != vec_ip1.end() ) { delete *iter; ++iter; } vec_ip1.clear(); iter = vec_ip2.begin(); while( iter != vec_ip2.end() ) { delete *iter; ++iter; } vec_ip2.clear(); system("Pause"); return 0;}