C++ 两个vector如何能很高效的求交集和并集?

liyukuneed 2011-03-17 09:10:31

两个vector<int>
如vector<int> a = {2, 34, 75, 876, 565, …}
vector<int> b = {54, 34, 3, 8, 6767, 78， …}

两个vector的元素个数不同，元素个数也挺多的，100个以上吧。

由于我的程序数据量很大，所以要求交集和并集的效率要高一些，大家帮帮忙，看看有没有高效些的方法。最好能给下代码。先谢谢了～～

...全文

1426 9 打赏收藏转发到动态举报

写回复

用AI写文章

9 条回复

切换为时间正序

请发表友善的回复…

发表回复

赵4老师 2011-03-17

打赏
举报

仅供参考

#include <algorithm>

#include <iostream>

#include <functional>

#include <cstring>

using namespace std;

int main() {

    char *Alphabet = "abcdefghijklmnopqrstuvwxyz" ;

    char *Vowels   = "aeiou" ;

    char *AlphaNum = "0123456789abcdef" ;

    char result[45] ;

    char *last ;



    int lenA  = strlen(Alphabet) ;

    int lenV  = strlen(Vowels  ) ;

    int lenAN = strlen(AlphaNum) ;



    cout << "Alphabet = " << Alphabet << endl ;

    cout << "Vowels   = " << Vowels   << endl ;

    cout << "AlphaNum = " << AlphaNum << endl ;



    cout << "\nusing non-predicate versions" << endl ;



    //non-predicate set_difference

    last = set_difference(Alphabet, Alphabet+lenA,

                          AlphaNum, AlphaNum+lenAN,

                          result) ;

    *last = 0 ;

    cout << "set_difference(Alphabet, AlphaNum) =  " << result << endl ;



    //non-predicate set_intersection

    last = set_intersection(Alphabet, Alphabet+lenA,

                            AlphaNum, AlphaNum+lenAN,

                            result) ;

    *last = 0 ;

    cout << "set_intersection(Alphabet, AlphaNum) =  " << result << endl ;



    //non-predicate set_symmetric_difference

    last = set_symmetric_difference(Alphabet, Alphabet+lenA,

                                    Vowels  , Vowels  +lenV,

                                    result) ;

    *last = 0 ;

    cout << "set_symmetric_difference(Alphabet, Vowels) =  " << result << endl ;



    //non-predicate set_union

    last = set_union(Alphabet, Alphabet+lenA,

                     AlphaNum, AlphaNum+lenAN,

                     result) ;

    *last = 0 ;

    cout << "set_union(Alphabet, AlphaNum) =  " << result << endl ;



    cout << "\nusing predicate versions" << endl ;



    //predicate set_difference

    last = set_difference(Alphabet, Alphabet+lenA,

                          AlphaNum, AlphaNum+lenAN,

                          result  , less<char>()) ;

    *last = 0 ;

    cout << "set_difference(Alphabet, AlphaNum) =  " << result << endl ;



    //predicate set_intersection

    last = set_intersection(Alphabet, Alphabet+lenA,

                            AlphaNum, AlphaNum+lenAN,

                            result  , less<char>()) ;

    *last = 0 ;

    cout << "set_intersection(Alphabet, AlphaNum) =  " << result << endl ;



    //predicate set_symmetric_difference

    last = set_symmetric_difference(Alphabet, Alphabet+lenA,

                                    Vowels  , Vowels  +lenV,

                                    result  , less<char>()) ;

    *last = 0 ;

    cout << "set_symmetric_difference(Alphabet, Vowels) =  " << result << endl ;



    //predicate set_union

    last = set_union(Alphabet, Alphabet+lenA,

                     AlphaNum, AlphaNum+lenAN,

                     result  , less<char>()) ;

    *last = 0 ;

    cout << "set_union(Alphabet, AlphaNum) =  " << result << endl ;



    return 0 ;

}