LeetCode(Google) 0276 Paint Fense

转载于 2018-04-21 03:56:45 发布 · 84 阅读

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原文链接：https://segmentfault.com/a/1190000014510852

本文介绍了解决LeetCode 276涂漆栅栏问题的方法，该问题要求计算给定数量的栅栏柱和可用颜色种类时，使得任意连续三个栅栏柱颜色都不完全相同的所有可能涂色方案的数量。通过动态规划方法，分别记录相邻两柱同色和不同色的情况，最终得出所有可能的涂色方案。

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LeetCode 276 Paint Fense

There is a fence with n posts, each post can be painted with one of the k colors.

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.

Note:
n and k are non-negative integers.

class Solution {
    public int numWays(int n, int k) {
        if (n == 0 || k == 0) return 0;
        if (n == 1) return k;
        // same[i] : 第i个post和第i-1个post颜色相同
        int[] same = new int[n];
        // diff[i] : 第i个post和第i-1个post颜色不同
        int[] diff = new int[n];
        same[0] = same[1] = k;
        diff[0] = k;
        diff[1] = k * (k - 1);
        for (int i = 2; i < n; ++i) {
            same[i] = diff[i-1];
            diff[i] = (k - 1) * same[i-1] + (k - 1) * diff[i-1];
        }
        return same[n-1] + diff[n-1];
    }
}