Painting Fence problem

[Fatema110]

Painting Fence problem

In a fence, with n posts and k available colors, we need to find out how many different
ways we can paint the fence so that at most two adjacent posts have the same color.
Output the answer modulo 10^9 + 7

How many posts are there on the fence? 3
How many colors are available? 7

The number of ways to color the given posts is 336

SAMPLE II
How many posts are there on the fence? 5
How many colors are available? 0

No color is available to paint!!!

Time Complexity: O(n) where 'n' is the number of posts to paint
Space Complexity: O(n)