我正在编写一个贪心算法(Python 3.x.x)来进行“珠宝盗窃”的问题。给定一系列的珠宝和价值,程序会选择最有价值的珠宝并放入袋中,直到达到袋的重量上限为止。这里有三个测试用例,其中两个完美运行。
每个测试用例都以相同的方式编写:第一行是袋的重量限制,其余行为元组(重量,价值)。
样例1(成功):
有人知道为什么第二种情况不起作用吗?非常感谢你的帮助。 编辑:第二种情况的预期结果是$6130。但我似乎只得到了$6090。
每个测试用例都以相同的方式编写:第一行是袋的重量限制,其余行为元组(重量,价值)。
样例1(成功):
10
3 4
2 3
1 1
示例情况2(不起作用):
575
125 3000
50 100
500 6000
25 30
代码:
def take_input(infile):
f_open = open(infile, 'r')
lines = []
for line in f_open:
lines.append(line.strip())
f_open.close()
return lines
def set_weight(weight):
bag_weight = weight
return bag_weight
def jewel_list(lines):
jewels = []
for item in lines:
jewels.append(item.split())
jewels = sorted(jewels, reverse= True)
jewel_dict = {}
for item in jewels:
jewel_dict[item[1]] = item[0]
return jewel_dict
def greedy_grab(weight_max, jewels):
#first, we get a list of values
values = []
weights = []
for keys in jewels:
weights.append(jewels[keys])
for item in jewels.keys():
values.append(item)
values = sorted(values, reverse= True)
#then, we start working
max = int(weight_max)
running = 0
i = 0
grabbed_list = []
string = ''
total_haul = 0
# pick the most valuable item first. Pick as many of them as you can.
# Then, the next, all the way through.
while running < max:
next_add = int(jewels[values[i]])
if (running + next_add) > max:
i += 1
else:
running += next_add
grabbed_list.append(values[i])
for item in grabbed_list:
total_haul += int(item)
string = "The greedy approach would steal $" + str(total_haul) + " of
jewels."
return string
infile = "JT_test2.txt"
lines = take_input(infile)
#set the bag weight with the first line from the input
bag_max = set_weight(lines[0])
#once we set bag weight, we don't need it anymore
lines.pop(0)
#generate a list of jewels in a dictionary by weight, value
value_list = jewel_list(lines)
#run the greedy approach
print(greedy_grab(bag_max, value_list))
有人知道为什么第二种情况不起作用吗?非常感谢你的帮助。 编辑:第二种情况的预期结果是$6130。但我似乎只得到了$6090。