Find maximum number in an array using recursion.

maxInArrayUsingRecursion.cpp

int max_in_array(vector<int> nums, int start_index, int end_index) {
    if (start_index == end_index) {
         return nums[start_index];
    }
    int maximum = max_in_array(nums, start_index+1, end_index);
    return max(nums[start_index], maximum);
}