SDE - 1

Tip 1: Need to revise topics related to assessment test.
Tip 2: Need to choose one option.
Tip 3: Based upon your knowledge you need to answer.

string Solution::multiply(string s1, string s2) {

int m1=s1.size();
int m2=s2.size();

if(s1=="0" || s2=="0")
{
return "0";
}

string ans="";
int carry=0;
string temp="";
for(int j=m2-1;j>=0;j--)
{
temp+='0';
string res=temp;
res.pop_back();

carry=0;

int val=s2[j]-'0';

for(int i=m1-1;i>=0;i--)
{
int x= (s1[i]-'0')*val;

x+=carry;

res.push_back('0' + (x%10));

carry=x/10;

}

while(carry>0)
{
res.push_back('0' + (carry%10));
carry=carry/10;
}

reverse(res.begin(),res.end());

if(ans=="")
{
ans=res;
continue;
}

carry=0;

// now add

string t="";

int k1=ans.size();
int k2=res.size();

int a=k1-1;
int b=k2-1;
val=0;
while(a>=0 || b>=0)
{
val=0;
if(a>=0)
{
val+=(ans[a]-'0');
a--;
}

if(b>=0)
{
val+=(res[b]-'0');
b--;
}

val+=carry;

t.push_back('0' + (val%10));

carry=val/10;

}

while(carry>0)
{
t.push_back('0' + (carry%10));
carry=carry/10;
}

reverse(t.begin(),t.end());
ans=t;

}

int i=0;

while(i {
i++;
}

if(i==ans.size())
{
return "0";
}

return ans.substr(i);

}