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  1. #include<iostream>
  2. using namespace std;
  3.  
  4.  
  5. string add(string a, string b)
  6. {
  7.    int al=a.size()-1;
  8.    int bl=b.size()-1;
  9.  
  10.    int carry=0;
  11.    string result="";
  12.  
  13.    while(al>=0 && bl>=0)
  14.     {
  15.     int temp = (int)(a[al] - '0') + (int)(b[bl] - '0') + carry ;
  16.     carry = 0;
  17.     if(temp > 9 )
  18.     {
  19.         carry=1;
  20.         temp=temp-10;
  21.     }
  22.  
  23.     result+=char(temp + '0');
  24.     al--;
  25.     bl--;
  26.     }
  27.  
  28.    while(al>=0)
  29.     {
  30.         int temp = (int)(a[al] - '0') + carry ;
  31.         carry = 0;
  32.         if(temp>9)
  33.         {
  34.             carry=1;
  35.             temp=temp%10;
  36.         }
  37.  
  38.         result+=char(temp + '0');
  39.         al--;
  40.     }
  41.  
  42.    while(bl>=0)
  43.     {
  44.         int temp = (int)(b[bl] - '0') + carry ;
  45.         carry = 0;
  46.         if(temp>9)
  47.         {
  48.             carry=1;
  49.             temp=temp%10;
  50.         }
  51.  
  52.         result+=char(temp + '0');
  53.         bl--;
  54.     }
  55.  
  56. if(carry)
  57.     result+="1";
  58.  
  59. string addition="";
  60.  
  61. for(int i=result.size()-1;i>=0;i--)
  62.     addition+=result[i];   // reversing the answer
  63.  
  64. return addition;
  65. }
  66.  
  67. string trim(string a)   // for removing leading 0s
  68. {
  69.    string res="";
  70.    int i=0;
  71.  
  72.    while(a[i]=='0')
  73.       i++;
  74.  
  75.    for(;i<a.size();i++)
  76.     res+=a[i];
  77.  
  78.    return res;
  79. }
  80.  
  81.  
  82. int main()
  83. {
  84.     string a = "999999999999";
  85.     string b = "1";
  86.  
  87.     cin>>a>>b;
  88.  
  89.     cout<<trim(add(a,b))<<endl;
  90. }
Success #stdin #stdout 0s 15240KB
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stdin
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Standard input is empty
stdout
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1000000000000
https://ideone.com/CxGift
language:
C++ (gcc 8.3)
created:
6 years ago
visibility:
public

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