Leetcode 415 Add Strings

Problem:

Given non-negative numbers num1 num2 and represented as String, return the sum of num1 num2 .

1. The length of both and is num1 num2 < 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 no built-in BigInteger library or convert the inputs to integer directly.

Summary:

The addition of two shaped numbers in the form of a string.

Analysis:

This problem is a regular problem, it is not difficult, just one person to add, pay attention to carry in the time with a carry.

1 classSolution {2  Public:3     stringAddStrings (stringNUM1,stringnum2) {4         intLen1 = Num1.size (), len2 =num2.size ();5         inti = len1-1, j = len2-1, k =0, carry =0;6         Charres[5200];7         8          while(I >=0&& J >=0) {9             intsum = Num1[i] + num2[j]-2*'0'+carry;Ten             if(Sum >9) { OneSum-=Ten; Acarry =1; -             } -             Else { thecarry =0; -             } -              -res[k++] = sum +'0'; +i--; j--; -         } +          A          while(I >=0) { at             intsum = Num1[i] + carry-'0'; -             if(Sum >9) { -Sum-=Ten; -carry =1; -             } -             Else { incarry =0; -             } to              +res[k++] = sum +'0'; -i--; the         } *          $          while(J >=0) {Panax Notoginseng             intsum = Num2[j] + carry-'0'; -             if(Sum >9) { theSum-=Ten; +carry =1; A             } the             Else { +carry =0; -             } $              $res[k++] = sum +'0'; -j--; -         } the          -         if(carry) {Wuyires[k++] ='1'; the         } -          Wures[k++] =' /'; -          About          for(i =0; I < K/2; i++) { $             CharTMP =Res[i]; -Res[i] = res[k-i-2]; -Res[k-i-2] =tmp; -         } A          +         stringResstr =string(res); the          -         returnResstr; $     } the};

The above for me to write the original code, the code is too lengthy, the following is a reference to the online Daniel code optimization code, a lot of code introduction:

1 classSolution {2  Public:3     stringAddStrings (stringNUM1,stringnum2) {4         intLen1 = Num1.size (), len2 =num2.size ();5         inti = len1-1, j = len2-1, carry =0;6         stringres ="";7         8          while(I >=0|| J >=0) {9             intSUM1 = i >=0? num1[i--]-'0':0;Ten             intsum2 = J >=0? num2[j--]-'0':0; One              A             intsum = sum1 + sum2 +carry; -Res.insert (Res.begin (), Sum%Ten+'0'); -carry = SUM/Ten; the         } -          -         returnCarry?"1"+Res:res; -     } +};

Leetcode 415 Add Strings