306. Additive Number

Additive number is a string whose digits can form Additive sequence.

A valid additive sequence should contain at least three numbers. Except for the first and numbers, each subsequent number in the sequence must is the sum of the preceding.

For example:
"112358"is a additive number because the digits can form an additive sequence: 1, 1, 2, 3, 5, 8 .

1 + 1 = 2, 1 + 2 = 3, 2 + 3 = 5, 3 + 5 = 8

"199100199"is also a additive number, the additive sequence is: 1, 99, 100, 199 .

1 + 99 = 100, 99 + 100 = 199

Note:numbers in the additive sequence cannot has leading zeros, so sequence 1, 2, 03 or is 1, 02, 3 invalid.

Given a string containing only digits ‘0‘-‘9‘ , write a function to determine if it's an additive number.

Follow up:
How would handle overflow for very large input integers?

1 classSolution {2  Public:3     BOOLCheckstringSTR1,stringSTR2,stringstr)4     {5     6 StringStream SS1;7         stringSTR3;8         Longnum1, num2, num3;9SS1 <<str1;TenSS1 >>NUM1; One ss1.clear (); ASS1 <<str2; -SS1 >>num2; - ss1.clear (); thenum3 = Num1 +num2; -SS1 <<num3; -SS1 >>STR3; - ss1.clear (); +      -cout << NUM1 <<" "<< num2 <<" "<< num3 <<Endl; +      A         if(STR3 = =str) at         { -             return true; -         } -         if(Str.size () < Str3.size () | | Str3.compare (STR.SUBSTR (0, Str3.size ()))! =0) -         { -             return false; in         } -         Else to         { +             returnCheck (str2, STR3, Str.substr (Str3.size ())); -         } the     } *      $     BOOLIsadditivenumber (stringnum) {Panax Notoginseng         intL =num.length (); -      the          for(inti =1; I <= (L-1) /2; ++i) +         { A             if(num[0] =='0'&& I >=2) the             { +                  Break; -             } $              for(intj =1; (L-i-J) >= I && (L-i-J) >= J; ++j) $             { -                 if(Num[i] = ='0'&& J >=2) -                 { the                      Break; -                 }Wuyi      the                 stringSTR1 = Num.substr (0, i); -                 stringSTR2 =Num.substr (i, j); Wu                  -                 if(Check (str1, str2, num.substr (i +J ))) About                 { $                     return true; -                 } -      -             } A         } +         return false; the     } -};

306. Additive number