基础算法 792.高精度减法

#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();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 = 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(){
    vector<int> A, B;
    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');
     
    if(cmp(A, B)){
        vector<int> C = sub(A, B);
        for(int i=C.size()-1;i>=0;--i) printf("%d",C[i]);
        
    }
    else{
        vector<int> C = sub(B, A);
        printf("-");
        for(int i=C.size()-1;i>=0;--i)printf("%d",C[i]);
    }
    return 0;
}