1001 A+B Format

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.

Sample Input:

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-1000000 9

Sample Output:

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-999,991

思路

• 使用Python处理字符串，一下子就简单了很多，当然这题用C++的string类拼接也可以，并不麻烦。不过我还是建议使用Python，因为所以的点都能过。
• 读取两个数，求它们的和，保存成字符串。
• 然后从后向前遍历，每隔三个位置，加一个逗号。
• 当再向前一个是负号的时候不用加逗号了。

代码

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a = str(sum(list(map(int,input().split()))))
count = 0
for i in range(len(a)-1,0,-1):
    count += 1
    if count % 3 == 0 and a[i-1]!='-':
        a = a[:i] + ',' + a[i:]
print(a)

太水了这题。