高精加高精

#include <bits/stdc++.h>
using namespace std;
vector<int> add(vector<int> &A,vector<int> &B) {
    vector<int> C;
    int t=0;
    for (int i=0; i<A.size() || i<B.size(); i++) {
        if (i < A.size()) t += A[i];
        if (i < B.size()) t += B[i];
        C.push_back(t%10);
        t /= 10;
    }
    if (t) C.push_back(t);
    return C;
}
int main() {
    string a,b;
    vector<int> A,B;
    cin >> a >> b;
    for (int i=a.size()-1; i>=0; i--) A.push_back(a[i]-'0');
    for (int i=b.size()-1; i>=0; i--) B.push_back(b[i]-'0');
    auto C=add(A,B);
    for (int i=C.size()-1; i>=0; i--) printf("%d",C[i]);
    return 0;
}

高精减高精

#include <bits/stdc++.h>
using namespace std;
bool cmp(vector<int> &A,vector<int> &B) {
    if (A.size() != B.size()) return A.size()>B.size();
    for (int i=A.size()-1; i>=0; i--) {
        if (A[i] != B[i]) {
            return A[i]>B[i];
        }
    }
    return true;
}
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;
}
int main() {
    string a,b;
    vector<int> A,B;
    cin >> a >> b;
    for (int i=a.size()-1 ; i>=0; i--) A.push_back(a[i]-'0');
    for (int i=b.size()-1; i>=0; i--) B.push_back(b[i]-'0');
    if (cmp(A,B)) {
        auto C=sub(A,B);
        for (int i=C.size()-1; i>=0; i--) printf("%d",C[i]);
    } else {
        auto C=sub(B,A);
        printf("-");
        for (int i=C.size()-1; i>=0; i--) printf("%d",C[i]);
    }  
    return 0;
}

高精乘低精

#include <bits/stdc++.h>
using namespace std;
vector<int> mul(vector<int> &A,int b) {
    vector<int> C;
    int t=0;
    for (int i=0; i<A.size() || t; i++) {
        if (i < A.size()) t += A[i]*b;
        C.push_back(t%10);
        t /= 10;
    }
    return C;
}
int main() {
    string a;
    int b;
    cin >> a >> b;
    if (b == 0) {
        cout << 0;
        return 0;
    }
    vector<int> A;
    for (int i=a.size()-1; i>=0; i--) A.push_back(a[i]-'0');
    auto C=mul(A,b);
    for (int i=C.size()-1; i>=0; i--) printf("%d",C[i]);
    return 0;
}

高精乘高精

#include <bits/stdc++.h>
using namespace std;
vector<int> a,b;
string x,y;
vector<int> mul(vector<int> &a,vector<int> &b) {
    vector<int> c;
    for (int i=0; i<a.size(); i++) {
        for (int j=0; j<b.size(); j++) {
            if (i+j < c.size()) c[i+j] += a[i]*b[j];
            else c.push_back(a[i]*b[j]);
        }
    }
    int t=0;
    for (int i=0; i<c.size(); i++) {
        t += c[i];
        c[i] = t%10;
        t /= 10;
    }
    while (t) {
        c.push_back(t%10);
        t /= 10;
    }
    while (c.size()>1 && c.back()==0) c.pop_back();
    return c;
}
int main() {
    cin >> x >> y;
    for (int i=x.size()-1; i>=0; i--) a.push_back(x[i]-'0');
    for (int i=y.size()-1; i>=0; i--) b.push_back(y[i]-'0');
    auto c=mul(a,b);
    for (int i=c.size()-1; i>=0; i--) cout << c[i];
    return 0;
}

高精除低精

#include <bits/stdc++.h>
using namespace std;
using namespace std;
vector<int> div(vector<int> &A,int b,int &r) {
    vector<int> C;
    r = 0;
    for (int i=A.size()-1; i>=0; i--) {
        r = r*10+A[i];
        C.push_back(r/b);
        r %= b;
    }
    reverse(C.begin(),C.end());
    while (C.size()>1 && C.back()==0) C.pop_back();
    return C;
}
int main() {
    string a;
    int b;
    cin >> a >> b;
    vector<int> A;
    for (int i=a.size()-1; i>=0; i--) A.push_back(a[i]-'0');
    int r;
    auto C=div(A,b,r);
    for (int i=C.size()-1; i>=0; i--) printf("%d",C[i]);
    cout << endl << r << endl;
}