pat 甲级 A1001 A+B Format python两种方法实现

pat 甲级 A1001 python两种方法实现

题目描述

Calculate a+b and output the sum in standard format – that is, the digits must be separated into groups of three by commas (unless there are less than four digits).
Input Specification:

Each input file contains one test case. Each case contains a pair of integers a and b where −10​6​​≤a,b≤10​6​​. The numbers are separated by a space.
Output Specification:

For each test case, you should output the sum of a and b in one line. The sum must be written in the standard format.

法1：（.format函数直接实现）

a, b = [int(x) for x in input().split()]
print("{:,}".format(a+b))

这就是：Python的简洁之处！ ，只需两行即可实现该功能！
具体.format函数的使用和功能，参看.format格式化函数

法2：（递归）

a, b = [int(x) for x in input().split()]
num = str(a + b)

def StdNum(num):
    if num[0]!= '-':
        if len(num) < 4:
            return num
        else:
            j = -1
            for i in range(len(num)):
                j -= 1
                p = num[j:]
                if len(p)==3:
                    return StdNum(num[:j]) + ',' + p
    else:
        if len(num) < 5:
            return num
        else:
            j = -1
            for i in range(len(num)):
                j -= 1
                p = num[j:]
                if len(p)==3:
                    #if num[j-1] != '-':
                    return StdNum(num[:j]) + ',' + p

print(StdNum(num))