ZH
RU
EN
ES
FR
DE
PT
AR
HI
🎉 恭喜！ 🎉
你出色地完成了任务！这是一个不小的挑战，但你找到了正确答案。你离编程大师又近了一步！继续保持，每一步都让你更强大。
课程 7. Two -dimensional arrays
难度：
任务«你需要推迟多久？»
💻 Python
你需要为10年制定预算。年度支出以二维数组的形式给出
Expenses [year] [Category] ，其中 year — 从0到9 （ categories 支出类别数为整数，始终等于5）。当前薪资 — salary 。第 n 年的薪资计算公式为 salary * (1 + p)^n ，其中 p — 薪资增长率（以小数表示，例如0.05代表5%）。找到最小的 p （精度为0.001），使得10年的总薪资不低于这10年的总支出。 输入格式
salry (物料编号)。以下是10行，每行包含5个物料编号 & mdash; 按类别划分的年度支出 输出格式
推导满足条件的最小值
p （材料编号），精度达到小数点后三位 示例
输入
3000
RN 200 200 200 200 200
RN 300 300 300 300 300
RN 400 400 400 400
RN 500 500 500 500 500
RN 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600 600
RN 700 700 700 700 700
RN 800 800 800 800 800
RN 900 900 900 900
RN 1000 1000 1000 1000 1000
RN 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100
输出
0.018
提示
min function
The min() function is your tool for quickly searching for the smallest element of several values or within a collection.
Syntax
min(iterable, *[, key, default])
min(arg1, arg2, *args[, key])
iterable: An iterable object (for example, a list, tuple, string, set).arg1, arg2, *args: One or more arguments passed directly for comparison.key(optional): A function that is applied to each element before comparison. The minimum will be searched based on the results of this function.default(optional): The value that will be returned ifiterableis empty. Ifdefaultis not specified, an attempt to find the minimum in an empty collection will cause the errorValueError.
Usage examples
-
With a single iterable object:
numbers = [3, 1, 4, 1, 5, 9] print(min(numbers)) # Output: 1 -
With multiple arguments:
print(min(3, 1, 4, 1, 5, 9)) # Output: 1 -
With the
keyparameter: Searching for an element by any of its properties.words = ["apple", "banana", "cherry"] # Finding the word with the shortest length print(min(words, key=len)) # Output: 'apple' -
With the
defaultparameter: Safe handling of potentially empty collections.empty_list = [] print(min(empty_list, default="empty")) # Output: 'empty'
Useful tips and subtleties:
- Comparing different types: Incomparable data types, such as a number and a string, cannot be compared.
min(5, "hello")will cause the errorTypeError. - How the
keyworks: It is important to understand thatkeyonly changes the value for comparison, but returns the original element. In the examplemin(words, key=len), the lengths (5, 6, 6) are compared, but the word 'apple' itself is returned. - Using
lambdafunctions withkey: For complex comparisons, it is convenient to use anonymouslambdafunctions. For example, to find a dictionary with the minimum value by the key 'age':people = [{'name': 'John', 'age': 25}, {'name': 'Jane', 'age': 22}] print(min(people, key=lambda person: person['age'])) # Output: {'name': 'Jane', 'age': 22} - String comparison: The strings are compared lexicographically (in alphabetical order).
min("a", "b", "A")returns'A', since capital letters have a smaller code in the symbol table.
Function max()
The max() function works similarly to min(), but returns the largest element from the passed arguments or collection.
Syntax
max(iterable, *[, key, default])
max(arg1, arg2, *args[, key])
The parameters (iterable, arg1, arg2, *args, key, default) have the same value as in the min() function.
Usage examples
-
With a single iterable object:
numbers = [3, 1, 4, 1, 5, 9] print(max(numbers)) # Output: 9 -
With multiple arguments:
print(max(3, 1, 4, 1, 5, 9)) # Output: 9 -
With the
keyparameter:words = ["apple", "banana", "cherry"] # Finding the word with the longest length print(max(words, key=len)) # Output: 'banana' -
With the
defaultparameter:empty_list = [] print(max(empty_list, default='N/A')) # Output: 'N/A'
Useful tips and subtleties:
- All the tips and subtleties applicable to
min()are also relevant formax(): avoid mixing types, uselambdafunctions for complex keys and keep in mind thedefault parameterfor empty collections. - If there are several identical maximum/minimum elements, the first one is returned. In the example,
max(words, key=len)the words "banana" and "cherry" have the same length of 6, butmaxreturns the first encountered 'banana'.
Function sum()
The sum() function is used to find the sum of numeric elements in an iterable object.
Syntax
sum(iterable, start=0)
iterable: An iterable object containing numbers (for example, a list, a tuple, a set).start(optional): The initial value that is added to the total amount. The default value is 0.
Usage examples
-
Sum of list/tuple/set elements:
numbers_list = [1, 2, 3, 4, 5] print(sum(numbers_list)) # Output: 15 -
Using the
startparameter:numbers = [1, 2, 3, 4, 5] # We start summing not from 0, but from 10 total = sum(numbers, 10) print(total) # Output: 25 (10 + 1 + 2 + 3 + 4 + 5)
Application to two-dimensional arrays (lists of lists)
sum() can be effectively used to process matrices, but with one important caveat.
- Wrong approach:
sum(matrix)will cause the errorTypeError, as Python will try to add the initial value0with the list[1, 2, 3]. - The right approach: You must first calculate the sum of each row, and then add these amounts.
# Two-dimensional array matrix = [ [1, 2, 3], [4, 5, 6], [7, 8, 9] ] # Sum of all array elements using a generator total_sum = sum(sum(row) for row in matrix) print(total_sum) # Output: 45
Useful tips and subtleties:
- For numbers only:
sum()only works with numeric types (int, float). An attempt to summarize a list of strings (sum(["a", "b"])) will result in aTypeError. - Summation
True/False:Trueis interpreted as1, andFalseas0. This can be used to count the true values in the collection.bools = [True, False, True, True] # 1 + 0 + 1 + 1 print(sum(bools)) # Output: 3 - "Flattening" the list of lists: The
startparameter can be cunningly used to combine lists, although it is less readable and efficient than other methods.
Warning: This method is not recommended for large lists due to poor performance.list_of_lists = [[1, 2], [3, 4], [5]] flat_list = sum(list_of_lists, []) print(flat_list) # Output: [1, 2, 3, 4, 5]
main.py
测试 1
测试 2
测试 3
测试 4
测试 5
测试 6
测试 7
测试 8
测试 9
测试 10
开发者解答
