sort numbers which has odd-index in vector

问题:

I want to sort numbers in vector which has odd-index (index starts from 0).

For example, if I enter this numbers; 1 6 5 7 3 2 0, program must returns this: 1 2 5 6 3 7 0.

My code

#include <iostream> #include <vector>  using namespace std;  int main() {     int eded, n, _temp;     size_t i;      cout << "Nece eded daxil edeceksiniz?" << endl << ">>> ";     cin >> n;      vector<int> v_eded;     v_eded.reserve(n); // n qeder bosh yer ayiriram vektor-da      cout << "Ededleri daxil edin:" << endl;      for (int i = 0; i < n; i++)     {         cin >> eded;         v_eded.push_back(eded);     }      for (i = 1; i < v_eded.size(); i+=2)     {         if (v_eded[i] > v_eded[i+2])         {             _temp = v_eded[i+2];             v_eded[i+2] = v_eded[i];             v_eded[i] = _temp;         }     }      for (auto j : v_eded)         cout << j << " ";      return 0; } 

It compiles without any warning and/or error. After inserting eded, I'm pressing Enter and program gives me this error:

I couldn't determine what's the problem. Please, explain me what's the wrong and how to solve this.

Best regards.

回答1:

You have out of bound access with

if (v_eded[i] > v_eded[i+2]) 

where only i < v_eded.size(), not i + 2

回答2:

this should more or less do it:

    #include <boost/iterator_adaptors.hpp>      using namespace std;      template<class Iter>     struct by_2_iterator     : boost::iterator_adaptor<by_2_iterator<Iter>, Iter>     {         by_2_iterator(Iter it, Iter limit)         : by_2_iterator::iterator_adaptor_(it)         , _limit(limit)         {}      private:          struct enabler {};  // a private type avoids misuse         friend class boost::iterator_core_access;          void advance(typename by_2_iterator<Iter>::difference_type n)         {             std::advance(this->base_reference(), n * 2);         }          void increment()         {             auto dist = _limit - this->base_reference();             if (dist == 1) {                 ++(this->base_reference());                 _was_half = true;             }             else {                 this->advance(1);                 _was_half = false;             }         }          void decrement()         {             if (_was_half) {                 --(this->base_reference());                 _was_half = false;             }             else {                 this->advance(-1);             }         }      private:         Iter _limit;         bool _was_half = false;     };      template<class Iter>     by_2_iterator<Iter>     make_by_2(Iter it, Iter e) {         return by_2_iterator<Iter>(it, e);     }       BOOST_AUTO_TEST_CASE(play_2sort)     {          std::vector<int> v { 1, 6, 5, 7, 3, 2, 0 };          auto b = make_by_2(begin(v)+1, end(v));         auto e = make_by_2(end(v), end(v));          std::sort(b, e);          std::copy(begin(v), end(v), ostream_iterator<int>(cout, ", "));         cout << endl;        } 

回答3:

I just edited my code and I used simple *select sort* algorithm.

#include <iostream> #include <vector>  using namespace std;  int main() {     int eded, n, _temp, min_i;     size_t i, j;      cout << "Nece eded daxil edeceksiniz?" << endl << ">>> ";     cin >> n;      vector<int> v_eded;     v_eded.reserve(n); // n qeder bosh yer ayiriram vektor-da      cout << "Ededleri daxil edin:" << endl;      for (int i = 0; i < n; i++)     {         cin >> eded;         v_eded.push_back(eded);     }      for (i = 1; i <= n; i += 2) // or you can replace " n " with v_eded.size()     {         min_i = i;         for (j = i; j < n; j += 2)         {             if (v_eded[j] < v_eded[min_i])                 min_i = j;              _temp = v_eded[i];             v_eded[i] = v_eded[min_i];             v_eded[min_i] = _temp;         }     }      cout << endl << endl;     for (auto v : v_eded)         cout << v << "  ";      return 0; } 

Thanks.

文章来源: sort numbers which has odd-index in vector