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 ;

 }