Question

Given a array of random integers, sort the odd elements in descending order and even numbers in ascending order.

Example input: (1,4,5,2,3,6,7)

Output: (7,5,3,1,2,4,6)

Optimize for time complexity.

Answer 1

Which language is it, C or C++ (I see both tags)

In C++, you can use std::sort() with appropriate ordering function. In C, qsort() works similarly:

#include <iostream>
#include <algorithm>
bool Order(int a, int b)
{
        if (a%2 != b%2) return a%2;
        else return a%2 ? b<a : a<b;
}
int main()
{
        int a[] = {1,4,5,2,3,6,7};
        size_t N = sizeof(a) / sizeof(a[0]);

        std::sort(a, a+N, Order);

        for(size_t i=0; i<N; ++i)
                std::cout << a[i] << ' ';
        std::cout << std::endl;

}