Paint House II — LeetCode 265 Python Solution

The problem

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.

Example

Input

costs = [[1,5,3],[2,9,4]]

Output

5

Explanation

Paint house 0 into color 0, paint house 1 into color 2. Minimum cost: 1 + 4 = 5;

Python solution

class Solution:
    def minCostII(self, costs: List[List[int]]) -> int:
        n, k = len(costs), len(costs[0])
        f = costs[0][:]
        for i in range(1, n):
            g = costs[i][:]
            for j in range(k):
                t = min(f[h] for h in range(k) if h != j)
                g[j] += t
            f = g
        return min(f)

Complexity

Pattern: Dynamic Programming

Define a state, write the transition, and stop recomputing the same subproblem. LeetCode 265. Paint House II is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Dynamic Programming.

The dynamic programming guide has the Python template for the pattern and the 481 LeetCode problems that use it.

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