415. Add Strings

Given two non-negative integers num1 and num2 represented as string, return the sum of num1 and num2.

Note:

  1. The length of both num1 and num2 is < 5100.
  2. Both num1 and num2 contains only digits 0-9.
  3. Both num1 and num2 does not contain any leading zero.
  4. You must not use any built-in BigInteger library or convert the inputs to integer directly.

 

字符串表示十进制数，求相加后的结果

 

C++（19ms）：

 1 class Solution {
 2 public:
 3     string addStrings(string num1, string num2) {
 4         int i = num1.length() - 1 ;
 5         int j = num2.length() - 1 ;
 6         int c = 0 ;
 7         string res = "" ;
 8         while(i >= 0 || j >= 0 || c == 1){
 9             if (i >= 0)
10                 c += num1[i--] - '0' ;
11             if (j >= 0)
12                 c += num2[j--] - '0' ;
13             res = to_string(c%10) + res ;
14             c/=10 ;
15         }
16         return res ;
17     }
18 };

 

java(25ms):

 1 class Solution {
 2     public String addStrings(String num1, String num2) {
 3         StringBuilder sb = new StringBuilder() ;
 4         int i = num1.length() - 1 ;
 5         int j = num2.length() - 1 ;
 6         int c = 0 ;
 7         while(i >= 0 || j >= 0 || c == 1){
 8             if (i >= 0)
 9                 c += num1.charAt(i--) - '0';
10             if (j >= 0)
11                 c += num2.charAt(j--) - '0';
12             sb.append(c%10) ;
13             c/=10 ;
14         }
15         return sb.reverse().toString() ;
16         
17     }
18 }

 

posted @ 2017-11-14 10:33  __Meng  阅读(135)  评论(0)  编辑  收藏  举报