【PAT甲】1001 A+B Format (20分) 格式化输出

problem

1001 A+B Format (20分) 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: -1000000 9 Sample Output: -999,991

将两个数字相加，用标准格式输出最终结果

solution

两数相加开始还以为是高精度有点烦，结果1e6的数据怎么加都不会超过int的。标准格式输出，想用string流但是不会（而且慢），想用除法和取模发现循环顺序不对，最后用了递归。（分三步优化）提交WA了第四个点，考虑特殊数据 0 0时没有输出 #include<iostream> using namespace std; void output(int c, int cnt){ if(!c)return ; if(cnt%3==0 && c/10!=0){ output(c/10,cnt+1); cout<<","; }else output(c/10,cnt+1); cout<<c%10; } int main(){ int a, b; cin>>a>>b; int c = a+b; if(c==0){ cout<<0<<endl; return 0; } if(c<0){ cout<<"-"; c = -c; } output(c,1); return 0; }