PAT程序设计题目——甲级1001（国际标准格式化数字）

题目原文链接是：http://www.patest.cn/contests/pat-a-practise/1001

翻译题目要求如下：

计算出两个整数的和并将结果标准化——以三位数为单位用,逗号分割，如不超过三位，则无逗号分隔。仿照国际化的数字显示标准。

输入：-1000000 9
输出：-999,991
　

动态拾取：从低到高逐个按位获取，根据正负数追加符号，最后把数组倒置，代码实现如下（用g++编译测试通过）：

#include <stdio.h>
#include <string.h>
#include <math.h>
#include <iostream>

using namespace std;

char result[100] = {0};
long a, b;

char* add( long a, long b ) 
{
  long num = a + b;
  bool have_nagetive = false;
  int length = 0;
  have_nagetive = ( num >= 0 ? false : true );
  num = fabs(num);

  while ( num > 0 )
  {
    int value = num%10;
    num /= 10;
    if ( (length+1)%4 != 0 )
    {
      sprintf( result+length, "%d", value );
      length++;
    }
    else
    {
      sprintf( result+length, ",%d", value );
      length+=2;
    }
  }
  if ( have_nagetive )
  {
    strcat( result, "-");
  }
  if ( length== 0 )
  {
    strcat( result, "0" );
  }
  for ( int i = 0; i < strlen(result) / 2; i++ )
  {
    char tmp = result[i];
    result[i] = result[strlen(result) - i - 1];
    result[strlen(result) - i - 1] = tmp;
  }
  return result;
}

int main()
{
  while(cin>>a>>b){ 
  //printf("Please input 2 digits:\n");
  //scanf("%ld %ld",&a,&b);
  printf("%s\n",add(a,b));
  }
  return 0;
}

　　

Python 2.0 代码实现如下：

#2016.3.11 nodified
class add:
 def __init__(self):
  self.a = 0
  self.b = 0
  self.result = []
 def reset(self):
  self.result = []

def Add():
 sum = int(add_instance.a + add_instance.b)
 is_nagative = (True if(sum < 0) else False)
 sum = abs(sum)
 length = 0
 add_instance.reset()
 while( sum > 0 ): 
  value = sum%10
  sum = sum/10
  if( (length+1)%4 is 0 ):
   add_instance.result.append(',')
   length += 2
  else:
   length += 1
  add_instance.result.append(value)
 if( is_nagative is True ):
  add_instance.result.append('-')
 if(length is 0):
  add_instance.result.append('0')
 add_instance.result.reverse() 
 
def _main():
 while True:
  try:
   a,b = raw_input().split(' ')
  except:
   break
  if( a is None or b is None ):
   break
  add_instance.a = int(a)
  add_instance.b = int(b)
  Add()
  for i in range(0,add_instance.result.__len__()):
   add_instance.result[i] = str(add_instance.result[i])
  str_res = ('').join(add_instance.result)
  print(str_res)

add_instance = add()
_main()

　　

大家给些参考意见，谢谢！