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[0];
    int exsum = 0;
    for (int i = 1; i < n; i++) {
        int tmp = max(insum, exsum);
        insum = exsum + arr[i];
        exsum = tmp;
    }
    return max(insum, exsum);
}

int main() {
    int arr[6] = {5, 5, 10, 100, 10, 5};
    cout << maxsum(arr, 6) << endl;
    return 0;
}