华为机试测试- 大数相加

方法一：

直接使用BigDecimal

方法二：字符串解析，注意stringBuilder.append(int x)这里的x最终会变成x字符串,而不是对应的char.

 1 import java.math.BigDecimal;
 2 import java.util.Scanner;
 3
 4
 5 public class Main {
 6     public static void main(String[] args) {
 7         Scanner scanner=new Scanner(System.in);
 8         String t1=scanner.next();
 9         String t2=scanner.next();
10         System.out.println(getStr(t1, t2));
11         scanner.close();
12     }
13
14     public static String getStr(String a,String b)
15     {
16         int l=a.length();
17         int s=b.length();
18         String longString=l>s?a:b;
19         String shortString=l<=s?a:b;
20         l=longString.length();
21         s=shortString.length();
22         longString=new StringBuilder(longString).reverse().toString();
23         shortString=new StringBuilder(shortString).reverse().toString();
24         StringBuilder stringBuilder=new StringBuilder();
25         boolean carry=false;
26         for(int i=0;i<s;i++)
27         {
28             char cl=longString.charAt(i);
29             char cs=shortString.charAt(i);
30             int il=cl-‘0‘;
31             int is=cs-‘0‘;
32             int nx=il+is+(carry?1:0);
33             if(nx>9)
34             {
35                 carry=true;
36                 stringBuilder.append((char)(‘0‘+nx-10));
37             }
38             else {
39                 carry=false;
40                 stringBuilder.append((char)(‘0‘+nx));
41             }
42         }
43         if(s==l && carry)
44         {
45             stringBuilder.append(‘1‘);
46             return stringBuilder.toString();
47         }
48         String str=longString.substring(s,l);
49         for(int i=0;i<str.length();i++)
50         {
51             char c=str.charAt(i);
52             int nx=c-‘0‘+(carry?1:0);
53             if(nx>9)
54             {
55                 carry=true;
56                 stringBuilder.append((char)(‘0‘+nx-10));
57             }
58             else {
59                 carry=false;
60                 stringBuilder.append((char)(‘0‘+nx));
61             }
62         }
63         if(carry)
64             stringBuilder.append(‘1‘);
65         return stringBuilder.reverse().toString();
66     }
67 }