lintcode-easy-Paint Fence

There is a fence with n posts, each post can be painted with one of the kcolors.
You have to paint all the posts such that no more than two adjacent fence posts have the same color.
Return the total number of ways you can paint the fence.

Notice

n and k are non-negative integers.

Example

Given n=3, k=2 return 6

      post 1,   post 2, post 3
way1    0         0       1
way2    0         1       0
way3    0         1       1
way4    1         0       0
way5    1         0       1
way6    1         1       0

public class Solution {
    /**
     * @param n non-negative integer, n posts
     * @param k non-negative integer, k colors
     * @return an integer, the total number of ways
     */
    public int numWays(int n, int k) {
        // Write your code here

        int[] diff = new int[n + 1];
        int[] same = new int[n + 1];

        diff[0] = 0;
        diff[1] = k;

        same[0] = 0;
        same[1] = 0;

        for(int i = 2; i <= n; i++){
            diff[i] = same[i - 1] * (k - 1) + diff[i - 1] * (k - 1);
            same[i] = diff[i - 1];
        }

        return diff[n] + same[n];
    }
}