粉刷墙纸的问题

"""
输入: [[17,2,17],[16,16,5],[14,3,19]]
输出: 10
解释: 将 0 号房子粉刷成蓝色，1 号房子粉刷成绿色，2 号房子粉刷成蓝色。
     最少花费: 2 + 5 + 3 = 10。

解题思路：
本题采用动态规划的方式，类似求两个字符串求最大公共子序列。其中，
定义dp数组，表示前n个房间涂i的最小费用:
price = [[0 for _ in range(colours)] for _ in range(houses + 1)] #包含base case
 #状态转移工程
price[house][colour] = min(
    matrix[house-1][colour] + price[house-1][other_0],
    matrix[house - 1][colour] + price[house - 1][other_1]
)
"""

def painting_house(matrix):
    houses = len(matrix)
    colours = len(matrix[0])
    # dp定义，前n个房间涂i的最小费用
    price = [[0 for _ in range(colours)] for _ in range(houses + 1)]
    other_0 = 0
    other_1 = 0
    for house in range(1, houses + 1):
        for colour in range(colours):
            if colour == 0:
                other_0 = 1
                other_1 = 2
            elif colour == 1:
                other_0 = 0
                other_1 = 2
            elif colour == 2:
                other_0 = 0
                other_1 = 1
            #状态转移工程
            price[house][colour] = min(
                matrix[house-1][colour] + price[house-1][other_0],
                matrix[house - 1][colour] + price[house - 1][other_1]
            )
    res = float('inf')
    for colour in range(colours):
        res = min(res, price[houses][colour])
    return res

if __name__ == "__main__":
    matrix = [[17, 2, 17], [16, 16, 5], [14, 3, 19]]
    res = painting_house(matrix)
    print(res)