Given a fence with n posts and k colors, find out the number of ways of painting the fence such that at most 2 adjacent posts have the same color. Since answer can be large return it modulo 10^9 + 7.
Explanation: We have following possible combinations:
Since, this is a function problem. You don't need to take any input, as it is already accomplished by the driver code. You just need to complete the function countWays() that takes n and k as parameters and returns the number of ways in which the fence can be painted.(modulo 109 + 7)
Expected Time Complexity: O(N). Expected Auxiliary Space: O(N).