Python algorithm problems (three) - Classic Function Problems

A topic ( the number of specified types of characters in the string of statistics ):

　　Assuming that all the characters are divided into three categories: letters, numbers and other characters. write a function, determining the type of the specified character and type count the number of the character strings. enter a main program

description:

　　Input formats:

　　The first line of the input string, the second line enter a character, not to any message.

　　Output formats:

　　Outputting a specified number of character types, such as input-output example.

　　Example O:

analysis:

　　First, we need to traverse the first line of the input string, and then determine which character type of each character, numeric or alphabetic (letter but also consider the case), or a special symbol, then the same character type of a character the number of the last character of the second row and the number of characters for input, and outputs the same to its type.

Code:

def function(s,ch):
    a=0
    b=0
    c=0
    for i in s:
        if ord('0')<=ord(i)<=ord('9'):
            a=a+1
        elif ord('a')<=ord(i)<=ord('z') or ord('A')<=ord(i)<=ord('Z'):
            b=b+1
        else:
            c=c+1
    if ord('0')<=ord(ch)<=ord('9'):
        return a
    elif ord('a')<=ord(ch)<=ord('z') or ord('A')<=ord(ch)<=ord('Z'):
        return b
    else:
        return c
s=input()
CH = INPUT ()
 Print ( " with the same type of characters% c There are% d. " % (CH, function (S, CH)))

Title bis (Standard Deviation):　

　　Write a function to calculate the standard deviation of a series of numbers.

　　Standard deviation is defined: a set of data S = S ₀ , S _{. 1} , S ₂ , ..., S _{n--. 1} , which is represented as a standard deviation , wherein several main

description:

　　Input formats:

　　In several same number of input lines, comma separated.

　　Output formats:

　　Standard deviation:

　　Example O:

analysis:

　　First, we need to calculate m, according to the formula, we can make m = SUM / length (SUM = SUM + X), so that B = B + (XM) ** 2 , it is possible to obtain d = sqrt (b / (length- 1)) , is the standard deviation.

Code:

from math import *
def fd(*a):
    sum = 0
    length = len(a)
    for x in a:
        sum+=x
    m = sum/length
    b = 0
    for x in a:
        b+=(x-m)**2
    return sqrt(b/(length-1))
nums=eval(input())
print("标准差为%.1f"%fd(*nums))

题目三（判断闰年）：

　　编写函数leap，根据“四年闰百年不闰，四百年又闰”判断是否闰年。在主程序输入一个年份，调用leap函数判断其是否为闰年，并输出判断结果。

描述：

　　输入格式：

　　输入一个代表年份的整数。

　　输出格式：

　　输出年份是否闰年的判断结果。

　　输入输出示例：

分析：

　　明确本题的判断条件，即y%4==0 and y%100!=0返回True，或y%4==0 and y%400==0返回True，之后再判断，若leap(y)==True，则为闰年，反之则不是。

代码：

def leap(y):
    if y%4==0:
        if y%100!=0:
            return True
        elif y%400==0:
            return True
    else:
        return False    
y=int(input())
if leap(y)==True:
    print("%d年是闰年"%y)
else:
    print("%d年不是闰年"%y)

题目四（斐波那契数列）：

　　大家都知道斐波那契数列，现在要求输入一个整数n，请你输出斐波那契数列的第n项。

描述：

　　输入格式：

　　输出格式：

　　[0, 1, 1, 2, 3, 5, 8, 13, 21, 34]

分析：　

　　我们要知道斐波那契数列即：1、1、2、3、5、8、13、21、34、……它的特点是该数列从第三项开始，每个数的值为其前两个数之和，即f(n)=f(n-2)+f(n+1)。

代码：

n=int(input())
def feibo(num):
    result=[0,1]
    for i in range(num-2):
        result.append(result[-2]+result[-1])
    return result
print(feibo(n))

Python algorithm problems (three) - Classic Function Problems

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