PAT 1001 Format

problem

1001 A+B Format (20)（20 point(s)）
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

Each input file contains one test case. Each case contains a pair of integers a and b where -1000000 <= a, b <= 1000000. The numbers are separated by a space.

Output

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

anwser

#include <iostream> 
int main(){
    int a, b;
    int c;
    int end[10];
    std::cin>>a>>b;
    c = a+b;
    if (c==0) {
        std::cout<<"0";
        return 0;
    }
    if (c<0) {
        std::cout<<"-";
        c = -c;
    }
    int index = 0;
    while(c>0){
        end[index++] = c%1000;
        c/=1000;
    }
    for(int i = index - 1; i >= 0; i--){
        if(i != index-1){
            if(end[i] == 0) 
                std::cout<<"000";
            if(end[i] > 99)
                std::cout<<end[i];
            else if(end[i] > 9){
                std::cout<<"0";
                std::cout<<end[i];
            }
            else if (end[i] > 0){
                std::cout<<"00";
                std::cout<<end[i];
            }
        }
        else 
            std::cout<<end[i]; 
        if (i != 0)
          std::cout<<",";
    }
    return 0;
}

experience

• 邊界條件要注意的
  • c ==0
• 除首個數字外 end[i] == 0 的狀況，而且要分類討論
• 首個數字不須要特殊處理