HDUacm 1002 A + B Problem II

problem description
    i have a very simple problem for you. given two integers a and b, your job is to calculate the sum of a + b.
input
    the first line of the input contains an integer t(1<=t<=20) which means the number of test cases. then t lines follow, each line consists of two positive integers, a and b. notice that the integers are very large, that means you should not process them by using 32-bit integer. you may assume the length of each integer will not exceed 1000.
output
    for each test case, you should output two lines. the first line is "case #:", # means the number of the test case. the second line is the an equation "a + b = sum", sum means the result of a + b. note there are some spaces int the equation. output a blank line between two test cases.
sample input
    2
　 1 2
    112233445566778899 998877665544332211
sample output
    case 1:
    1 + 2 = 3
 
    case 2:
    112233445566778899 + 998877665544332211 = 1111111111111111110
 
code:
 1 #include <stdio.h>
 2 #include <string.h>
 3 main()
 4 {
 5     char a1[1001]={'\0'},b1[1001]={'\0'};
 6     int a2[1001],b2[1001],sum[1001];
 7     int n,i;        //n 总次数,i 第i次
 8     int la,lb,j,k,m,r;
 9
10     scanf("%d",&n);
11     i=1;
12     while(i<=n)
13     {
14         for(j=0;j<1001;j++) //初始化
15             sum[j]=0;
16         for(j=0;j<1001;j++)
17             a2[j]=0;
18         for(j=0;j<1001;j++)
19             b2[j]=0;
20         scanf("%s",&a1);
21         scanf("%s",&b1);
22         la=strlen(a1);
23         lb=strlen(b1);
24         r=1;
25         for(j=la-1;j>=0;j--) //类型转换,将数字位置逆序
26         {
27             a2[r]=a1[j]-48;
28             r++;
29         }
30         r=1;
31         for(j=lb-1;j>=0;j--)
32         {
33             b2[r]=b1[j]-48;
34             r++;
35         }
36
37         if(la>lb)  //以较大数的长度进行相加
38             k=la;
39         else
40             k=lb;
41         for(j=1;j<=k;j++)
42         {
43             sum[j]=sum[j]+a2[j]+b2[j];
44             if(sum[j]>=10)  //进位
45             {
46                 sum[j]=sum[j]-10;
47                 m=j+1;
48                 sum[m]++;
49             }
50         }
51        
52         printf("case %d:\n",i);  //输出结果，注意数字输出顺序
53         for(j=la;j>0;j--)
54         {
55             printf("%d",a2[j]);
56         }
57         printf(" + ");
58         for(j=lb;j>0;j--)
59         {
60             printf("%d",b2[j]);
61         }
62         printf(" = ");
63         if(sum[k+1])
64             k++;
65         for(j=k;j>0;j--)
66         {
67             printf("%d",sum[j]);
68         }
69         printf("\n");
70         if(i<n)
71             printf("\n");
72    
73         i++;
74     }
75 }

tips:
    1、本题为大整数相加类型，我先将大整数作为字符串读取，然后逐位转换为int型数，最后按位模拟求值；
    2、多次读取字符时，务必注意对数组进行初始化操作（为此我牺牲了近半小时的时间debug）；
    3、注意可能存在的最高位的进位输出；
    4、output a blank line between two test cases. --需要判断case数目；
    5、you may assume the length of each integer will not exceed 1000. --将数组定义的大于题目范围，防止溢出；
    6、字符串或char型数组的初始化可以使用‘\0’。

 

作者 任琦磊