高精减
cpp
vector<int> sub(vector<int>&A,vector<int> &B){
vector<int> C;
int t=0;
for(int i=0;i<A.size();i++){
t=A[i]-t;
if(i<B.size())t-=B[i];
C.push_back((t+10)%10);
if(t<0)t=1;
else t=0;
}
while(C.size()>1&&C.back()==0)C.pop_back();
return C;
}