LintCode 栅栏染色题目分析代码

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
        if (n == 0)
            return 0;
        if (n == 1)
            return k;
        if (n == 2)
            return k*k;
        int pre = k;
        int now = k*k;
        for (int i = 3; i <= n; i++)
        {
            int tmp = now;
            now = (pre+now) * (k-1);
            pre = tmp;
        }
        return now;
    }
}