2023-8-13 高精度减法

题目链接：高精度减法

#include 
#include 

using namespace std;


bool cmp(vector &A, vector &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 sub(vector &A, vector & B)
{
    vector 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 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;
}