[LeetCode 265] Paint House II
There are a row of n houses, each house can be painted with one of the k colors. The cost of painting each house with a certain color is different. You have to paint all the houses such that no two adjacent houses have the same color.
The cost of painting each house with a certain color is represented by a n x k cost matrix.
For example,
costs[0][0] is the cost of painting house 0 with color 0;
costs[1][2] is the cost of painting house 1 with color 2, and so on...
Find the minimum cost to paint all houses.
Note:
All costs are positive integers.
Follow up:
Could you solve it in O(nk) runtime?
DiffcultyHard
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Analysis
这道题是之前那道Paint House的拓展，那道题只让用红绿蓝三种颜色来粉刷房子，而这道题让我们用k种颜色，这道题不能用之前那题的解法，会TLE。这题的解法的思路还是用DP，但是在找不同颜色的最小值不是遍历所有不同颜色，而是用min1和min2来记录之前房子的最小和第二小的花费的颜色，如果当前房子颜色和min1相同，那么我们用min2对应的值计算，反之我们用min1对应的值，这种解法实际上也包含了求次小值的方法，感觉也是一种很棒的解题思路
下面这种解法不需要建立二维dp数组，直接用三个变量就可以保存需要的信息即可