题目

链接：PAT (Advanced Level) Practice 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 ​​ . 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:

-1000000 9

Sample Output:

-999,991

思路

题目大意是输入两个取值范围在和之间的整数，求它们的和，并输出，输出格式要每隔3位数输出一个逗号，如示例。
所以思路就是分多次输出，因为两数和最大也只有7位数，所以穷举各种可能性即可。

代码

#include<stdio.h>

int main(){
  int a, b, sum;
  scanf("%d %d", &a, &b);
  sum = a + b;
  if(sum < 0){
    printf("-");
    sum = -sum;
  }
  
  if(sum >= 1000000){      //当位数大于6时
    printf("%d,%03d,%03d", sum / 1000000, sum % 1000000 / 1000, sum % 1000);
  }
  else if(sum >= 1000){    //当位数大于3小于6时
    printf("%d,%03d", sum / 1000, sum % 1000);
  }
  else{                    //当位数小于等于3时
    printf("%d", sum);
  }
  return 0;
}

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