巧用nth_element求容器前n%大小的那个数

 1 #include <algorithm>

 2 #include <vector>

 3 #include <iostream>

 4 #include <string>

 5 #include <numeric>

 6 std::string::size_type stringLengthSum(std::string::size_type sumSoFar, const std::string& s)

 7 {

 8     return sumSoFar += s.size();

 9 }

10 int main()

11 {

12     std::vector<int> v{1,2,3,4,5,6,7,8,9,10,11,12};

13     auto begin = v.begin();

14     auto end = v.end();

15     decltype(begin) goodPosition;

16     goodPosition = begin + 0.3 * v.size();

17     nth_element(begin, goodPosition, end);

18     std::cout << *goodPosition << std::endl;

19     return 0;

20 }