我有这个代码来计算最小数量的硬币从一个总和与给定的名单表示。
例如:minimum change for 69 with denomiations [25,10,5,1] : [25, 25, 10, 5, 1, 1, 1, 1]
def get_min_coin_configuration(sum=None, coins=None, cache={}):
#if cache == None: # this is quite crucial if its in the definition its presistent ...
# cache = {}
if sum in cache:
return cache[sum]
elif sum in coins: # if sum in coins, nothing to do but return.
cache[sum] = [sum]
return cache[sum]
elif min(coins) > sum: # if the largest coin is greater then the sum, there's nothing we can do.
#cache[sum] = []
#return cache[sum]
return []
else: # check for each coin, keep track of the minimun configuration, then return it.
min_length = 0
min_configuration = []
for coin in coins:
results = get_min_coin_configuration(sum - coin, coins, cache)
if results != []:
if min_length == 0 or (1 + len(results)) < len(min_configuration):
#print "min config", min_configuration
min_configuration = [coin] + results
#print "min config", min_configuration
min_length = len(min_configuration)
cache[sum] = min_configuration
return cache[sum]
if __name__ == "__main__":
print "minimum change for 69 with denomiations [25,10,5,1] by recursive : ",get_min_coin_configuration(69,[25,10,5,1])
print "*"*45
print "minimum change for 7 with denomiations [4,3,1] by recursive : ",get_min_coin_configuration(7,[4,3,1])
当我注释掉main中的任何一个print语句时,程序似乎运行良好。 当我有两个函数调用时,它打印错误。在main中注释掉print语句,你就会看到它正确地打印出最小的硬币。你知道吗
minimum change for 69 with denomiations [25,10,5,1] by recursive : [25, 25, 10, 5, 1, 1, 1, 1]
*********************************************
minimum change for 7 with denomiations [4,3,1] by recursive : [5, 1, 1]
为每组面额传入一个单独的缓存
问题是,缓存已经知道如何将7更改为5,1,1,所以它只返回。。。缓存不知道5已不在面值集中。。。你知道吗
字典就像列表一样是可变的。。。这应该说明问题所在
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