osWHBm - Online C++0x Compiler & Debugging Tool

#include <bits/stdc++.h>
using namespace std;

int solve(int *arr, int n){
    if(n <= 3) return 0;

    int even[n], odd[n];
    int evencnt = 0, oddcnt = 0;

    for(int i = 0; i < n; i++){
        if(i % 2 == 0){
            even[evencnt++] = arr[i];
        } else {
            odd[oddcnt++] = arr[i];
        }
    }

    if(evencnt < 2 || oddcnt < 2) return 0;

    sort(even, even + evencnt); // ascending
    sort(odd, odd + oddcnt);    // ascending

    return even[evencnt - 2] + odd[oddcnt-2]; // second largest even + second smallest odd
}

int main() {
    int n;
    cin >> n;
    int *arr = new int[n];
    for(int i = 0; i < n; i++){
        cin >> arr[i];
    }

    cout << solve(arr, n);
    return 0;
}