AcWing 数位DP相关问题 1083. Windy数

import sys
sys.stdin = open('data.txt', 'r')


# 小于等于n的合法的数值个数
def get_num(n):
    if n == 0:
        return 0

    arr = []
    val = n
    while val:
        arr.append(val % 10)
        val //= 10

    # 前i位做选择，合法的数值个数
    # 约束条件：更高的一位选择数值是higher_val
    # 所有更高位全部选择最大值的标记是all_higher_max
    # 所有更高位全部选择是0标记是all_higher_zero
    from functools import lru_cache
    @lru_cache(typed=False, maxsize=128000000)
    def dp(i, higher_val, all_higher_max, all_higher_zero):
        if i == 0:
            upper_bound = arr[i] if all_higher_max else 9
            lower_bound = 1 if all_higher_zero else 0

            if all_higher_zero:
                return max(0, upper_bound - lower_bound + 1)
            else:
                cnt = 0
                for cur_val in range(lower_bound, upper_bound + 1):
                    if abs(cur_val - higher_val) >= 2:
                        cnt += 1
                return cnt

        else:
            upper_bound = arr[i] if all_higher_max else 9
            lower_bound = 0

            if all_higher_zero:
                ans = 0
                for cur_val in range(lower_bound, upper_bound + 1):
                    ans += dp(i-1, cur_val, all_higher_max and cur_val == arr[i], all_higher_zero and cur_val == 0)
                return ans

            else:
                ans = 0
                for cur_val in range(lower_bound, upper_bound+1):
                    if abs(cur_val - higher_val) >= 2:
                        ans += dp(i-1, cur_val, all_higher_max and cur_val == arr[i], all_higher_zero and cur_val == 0)
            return ans

    return dp( len(arr)-1, 0, True, True )


while True:
    try:
        a, b = map(int, input().split())
    except:
        break

    print( get_num(b) - get_num(a-1) )