Wrong ans for
A “5131848155574784703269632922904933776792735241197982102373370” B “56675688419586288442134264892419611145485574406534291250836”.
Can someone tell me what is wrong with my code?
string add(string ans, string prev)
{
int n = ans.size(), m = prev.size();
if(n> m)
{
while(n > m)
{
prev+= ‘0’ ;
m++;
}
}
n = ans.size();
m = prev.size();
//cout<<“ans = “<<ans<<” prev= “<<prev<<” “;
string s =””;
int carry = 0;
for(int i = 0 ; i < n; i++)
{
s+=to_string(((ans[i] - ‘0’)+(prev[i] - ‘0’) + carry)%10);
//cout<<"S = “<<s<<” ";
carry = ((ans[i] - '0')+(prev[i] - '0'))/10;
//cout<<"carry = "<<carry<<" ";
//}
}
if(carry)
{
s += to_string(carry);
}
//cout<<"s = "<<s<<" " ;
return s;
}
string Solution::multiply(string A, string B) {
int m = A.size(), n = B.size();
int x =0;
while(A[x] == '0')
{
A.erase(A.begin());
x++;
}
x = 0;
while(B[x] == '0')
{
B.erase(B.begin());
x++;
}
m = A.size();
n = B.size();
if(n == 0 || m == 0) return "0";
if(n > m)
{
return multiply(B, A);
}
reverse(A.begin(), A.end());
reverse(B.begin(), B.end());
string prev = "";
for(int i = 0 ; i < n; i++)
{
string ans= "";
int c = 0;
for(int j = 0 ; j < m; j++)
{
int a = (A[j] -'0') * (B[i] - '0');
int b = (a+c)%10;
ans += to_string(b);
//cout<<"ans = "<<ans<<" ";
if((A[i] -'0') * (B[i] - '0') > 9){
c = (A[i] -'0') * (B[i] - '0');
c = c/10;
}
}
if(c)
{
ans += (c + '0') ;
c = 0;
}
for(int n = 0; n < i; n++)
{
ans = '0' + ans;
}
//cout<<"after 1 digit multiplication "<<ans<<" ";
if(i ==0 ) prev = ans;
else
{
prev = add(ans, prev);
}
//cout<<"prev after addition is "<<prev<<" ";
}
//cout<<"prev = "<<prev<<" ";
reverse(prev.begin(), prev.end());
//cout<<"reversed = ";
//cout<<"prev = "<<prev<<" ";
int i = 0;
while(prev[i] == '0')
{
prev.erase(prev.begin());
}
return prev;
}
