Question

如何通过汇总键的值直到其达到50，然后将这些键写入文件来遍历字典。

例如：

fruits={'mangoes':10,'banana':20,'orange':20,'grapes':40,'apple':10,'strawberry':20,'cherry':30}

输出应该是多袋，每批最多有50个水果。

在此示例中：

bag1: 
mangoes,
banana,
orange

bag2:
grapes,
apple

bag3:
strawberry,
cherry

Answer 1

如果您只希望按字典顺序排列，则可以执行以下操作：

def bags(fruits, max_size):
    bag = []
    current_size = 0
    for name, count in fruits.items():
        if count + current_size > max_size:
            yield bag
            bag = []
            current_size = 0
        bag.append(name)
        current_size += count
    if bag:
        yield bag

for bag in bags(fruits, 50):
    print bag

Answer 2

所以我只是写了一些可以递归地跟踪元素和当前总和的东西。我认为它将为每个子选项提供每个选项。然后，它仅使用生成器项目构建袋子。（Python 3，用于yeild from）

def subset_sum(fruits, target, partial=[], partial_sum=0):
    if partial_sum == target:
        yield partial
    if partial_sum >= target:
        return
    for i, n in enumerate(fruits):
        remaining = fruits[i + 1:]
        yield from subset_sum(remaining, target, partial + [n], partial_sum + n[1])

if __name__ == "__main__":
    fruits={'mangoes':10,'banana':20,'orange':10,'grapes':40,'apple':10,'strawberry':20,'cherry':30}
    fruits=tuple((k,v) for k,v in fruits.items())
    result = subset_sum(fruits,50)
    for i, n in enumerate(result):
        print('Bag {}: {}'.format(i, ' '.join([f[0] for f in n])))

Bag 0: mangoes banana orange apple
Bag 1: mangoes banana strawberry
Bag 2: mangoes orange apple strawberry
Bag 3: mangoes orange cherry
Bag 4: mangoes grapes
Bag 5: mangoes apple cherry
Bag 6: banana orange strawberry
Bag 7: banana apple strawberry
Bag 8: banana cherry
Bag 9: orange grapes
Bag 10: orange apple cherry
Bag 11: grapes apple
Bag 12: strawberry cherry

通过汇总值遍历字典键

2 个答案: