python 基础算法
作者：互联网
1 #算法：解决问题的方法和步骤
2
3 #排序算法
4 #选择排序
5 def select(items, comp = lambda x,y : x <y):
6 #通过隐藏函数lambda判断两个数的大小
7 items = items[:]
8 for i in range(len(items) - 1):
9 min = i
10 for j in range(i+1, len(items)):
11 if comp(items[j], items[min]):
12 #获得j以后的最小值
13 min = j
14 items[i], items[min] = items[min], items[i]
15 #将判断得到的最小值放在前面
16 return items
17
18 #冒泡排序
19 def maopao(items, tem = lambda x, y : x > y):
20 items = items[:]
21 for i in range(len(items) - 1):
22 exambine = False
23 for j in range(len(items) - 1 - i):
24 #把最大的放在最后
25 if tem(items[j], items[j + 1]):
26 items[j], items[j + 1] = items[j+1], items[j]
27 exambine = True
28 if not exambine:
29 break
30 return items
31
32 #搅拌排序
33 def jban_select(items, stm = lambda x, y : x > y):
34 items = items[:]
35 for i in range(len(items)-1):
36 exim = False
37 for j in range(len(items) - 1 -i):
38 #把最大的放到最后
39 if stm(items[j], items[j+1]):
40 items[j], items[j+1] = items[j+1], items[j]
41 exim = True
42 if exim:
43 exim = False
44 for x in range(len(items)-2-i, 0, -1):
45 #把最小的放在最前面
46 if stm(items[x-1], items[x]):
47 items[x-1], items[x] = items[x],items[x-1]
48 exim = True
49 if not exim:
50 break
51 return items
52
53 #归并排序
54 def collect(items1, items2, comp = lambda x,y : x <y):
55 items = []
56 #print('items1%s' %items1)
57 #print('items2%s' %items2)
58 index1, index2 = 0, 0
59 while index1 < len(items1) and index2 < len(items2):
60 if comp(items1[index1], items2[index2]):
61 items.append(items1[index1])
62 index1 += 1
63 else:
64 items.append(items2[index2])
65 index2 += 1
66 items += items1[index1:]
67 items += items2[index2:]
68 #print('items%s'%items)
69 return items
70 def after(items):
71 return sort(list(items))
72
73 def sort(items):
74 if len(items) < 2:
75 return items
76 mid = len(items) // 2
77 left = sort(items[:mid])
78 right = sort(items[mid:])
79 #print('left:%s' %left)
80 #print('right%s' %right)
81 return collect(left, right)
82 print(after([23,45,2,4,5232,1]))
83
84 #查找算法
85 #顺序查找
86 def function(items, key):
87 for number, value in enumerate(items):
88 if value == key:
89 return number
90 return -1 #若不存在key，安全退出
91
92 #折半查找
93 def half_holt(items, key):
94 #items为从小到大排列
95 start, end = 0, len(items)-1
96 while start < end:
97 mid = (start + end) // 2
98 if key < items[mid]:
99 end = mid -1
100 elif key > items[mid]:
101 start = mid +1
102 else:
103 return mid
104 return -1
105
106 #穷举法(百元百鸡)
107 #公鸡5元一只，母鸡3元一只，小鸡1元3只
108 for i in range(20):
109 for j in range(33):
110 k = 100 - i - j
111 if i*5 + j*3 + k/3 == 100 and k % 3 == 0:
112 print('公鸡%d只，母鸡%d只，小鸡%d只' %(i, j, k))
113
114 #五人分鱼
115 fish = 6
116 while True:
117 total = fish
118 enough = True
119 for _ in range(5):
120 #保证5次分鱼都是一样的
121 if (total-1) % 5 == 0:
122 total = (total - 1) // 5 *4
123 else:
124 enough = False
125 break
126 if enough:
127 print(fish)
128 break
129 fish += 5
130
131 #贪婪法(不追求最优解，快速找到满意解)
132 class power_weight():
133
134 def __init__(self, name, price, weight):
135 self.name = name
136 self.weight = weight
137 self.price = price
138 @property
139 def thing_count(self):
140 return self.price / self.weight
141
142 def ip_thing():
143 name, weight, price = input('拥有的物品及属性：').split()
144 #split() 通过指定分隔符对字符串进行切片
145 return name, int(weight), int(price)
146
147 def main():
148 max_weight, mun_thing = map(int, input('总重和总的物品件数：').split())
149 #map(function, iterable, ...),对序列根据方法排序
150 thing_rate = []
151 for _ in range(mun_thing):
152 thing_rate.append(power_weight(*ip_thing()))
153 thing_rate.sort(key=lambda x : x.thing_count ,reverse = True)
154 #key=lambda x : x.thing_count 不太懂
155 total_weight = 0
156 total_price = 0
157 print('ok')
158 for thing in thing_rate:
159 if total_weight + thing.weight <= max_weight:
160 print(f'小偷带走了{thing.name}')
161 total_weight += thing.weight
162 total_price += thing.price
163 print(f'总价值{total_price}美元')
164
165 if __name__ == '__main__':
166 main()
167
168 #快速排列(选择枢轴对元素进行划分，左边都比枢轴小右边都比枢轴大)
169 def main(items, comp = lambda x, y : x <= y):
170 items = items[:]
171 func1(items, 0, len(items) - 1, comp)
172 return items
173
174 def func1(items, start ,end, comp):
175 if start < end:
176 pol = func2(items, start, end, comp)
177 func1(items, start, pol-1, comp)
178 func1(items, pol +1, end,comp)
179
180 def func2(items, start, end, comp):
181 boss = items[end]
182 i = start -1
183 for j in range(start, end):
184 if comp(items[j], boss):
185 i +=1
186 items[i], items[j] = items[j], items[i]
187 items[i+1], items[end] = items[end], items[i+1]
188 return i+1
189
190 #动态规则
191 items = list(map(int, input('输入数列').split()))
192 overall = part = items[0]
193 for i in range(1, len(items)):
194 part = max(items[i], part+items[i])
195 overall = max(part, overall)
196 print(overall)
标签：weight,python,items,基础,range,thing,算法,total,def 来源： https://www.cnblogs.com/Uriel-w/p/14908230.html