[练习] 高精度加减乘除

高精度加法 

 

#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>
using namespace std;

vector<int> A,B;

vector<int> sum(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;
    cin >> a;
    cin >> 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=sum(A,B);
    for (int i = C.size()-1; i >= 0; i -- ) cout << C[i];
    return 0;
}

高精度减法 

 

#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>
using namespace std;

vector<int> A,B;

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;//后一位向这一位借的
    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);//此时t≥0: 直接取t t<0: 取(t+10)的个位数
        
        if(t<0) t=1;
        else t=0;
    }
    while(C.size()>1 && C.back()==0) C.pop_back();//删去无用的"0"
    return C;
}
int main()
{
    string 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');
    
    vector<int> C;
    if(cmp(A, B)){//保证 大减小
        C=sub(A, B);
    }else{
        cout << '-';
        C=sub(B, A);
    }
    
    for (int i = C.size()-1; i >= 0; i -- ) cout << C[i];
    
    return 0;
}

高精度乘法

 

#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>
using namespace std;

vector<int> A,C;

void mul(vector<int>& A, int b)
{
    int t=0;
    for (int i = 0; i < A.size() || t>0; i ++ )
    {
        if(i < A.size()) t = A[i]*b+t;
        C.push_back(t%10);
        t /= 10;
    }
    while (C.size()>1 && C.back()==0) C.pop_back();
}

int main()
{
    string a;
    int b;
    cin >> a >> b;

    for (int i = a.size()-1; i >= 0; i -- ) A.push_back(a[i]-'0');
    mul(A,b);
    for (int i = C.size()-1; i >= 0; i -- ) cout << C[i];
    return 0;
}

高精度除法

 

#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>
using namespace std;

vector<int> A,C;

void div(vector<int>& A, int b,int& r)
{
    r=0;
    for (int i = 0; i < A.size(); 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();
}

int main()
{
    string a;
    int b,r=0;
    cin >> a >> b;

    for (int i = 0; i < a.size(); i ++ ) A.push_back(a[i]-'0');
    div(A,b,r);
    for (int i = C.size()-1; i >= 0; i -- ) cout << C[i];
    cout << endl << r;
    return 0;
}