Data Structure Array: Maximum sum such that no two elements are adjacent

http://www.geeksforgeeks.org/maximum-sum-such-that-no-two-elements-are-adjacent/

 #include <iostream>
 #include <vector>
 #include <algorithm>
 #include <queue>
 #include <stack>
 #include <string>
 #include <fstream>
 #include <map>
 using namespace std;

 int maxsum(int arr[], int n) {
     int insum = arr[];
     int exsum = ;
     for (int i = ; i < n; i++) {
         int tmp = max(insum, exsum);
         insum = exsum + arr[i];
         exsum = tmp;
     }
     return max(insum, exsum);
 }

 int main() {
     int arr[] = {, , , , , };
     cout << maxsum(arr, ) << endl;
     return ;
 }