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 an `n x k`

cost matrix costs.

- 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...

Return *the minimum cost to paint all houses*.

**Example 1:**

Input:costs = [[1,5,3],[2,9,4]]Output:5Explanation:Paint house 0 into color 0, paint house 1 into color 2. Minimum cost: 1 + 4 = 5; Or paint house 0 into color 2, paint house 1 into color 0. Minimum cost: 3 + 2 = 5.

**Example 2:**

Input:costs = [[1,3],[2,4]]Output:5

**Constraints:**

`costs.length == n`

`costs[i].length == k`

`1 <= n <= 100`

`1 <= k <= 20`

`1 <= costs[i][j] <= 20`

**Follow up:** Could you solve it in `O(nk)`

runtime?