题目描述

本人菜鸟一枚，各位大佬轻喷

C++ 代码

#include <iostream>
#include <string>
using namespace std;
 bool check(int q[],int p[],int n){
        for(int i=n-1;i>=0;i--){
            if(q[i]>p[i])return false;
            if(q[i]==p[i])continue;
            if(q[i]<p[i])return true;
        }
        return false;
    }//检查q[i]代表的数是否小于p[i]代表的数

    int check0 (int f[],int n){
        if(f[n-1]!=0)return n-1;
        else for(int i=n-1;i>=0;i--){
            if(f[i]!=0)return i+1;
            else continue;
        }
    }
   bool check_all_0(int f[],int n){
        for(int i=0;i<n;i++){
            if(f[i]!=0)return false;
        }
        return true;
    }
int main() {
    const int N = 1e5 + 10;
    string a, b;
    int q[N] = { 0 }, p[N] = { 0 };
    cin >> a >> b;
    int n = a.size(), m = b.size();
    for (int i = 0; i < n; i++)q[i] = a[n-i-1]-48;
    for (int i = 0; i < m; i++)p[i] = b[m-i-1]-48;
    int f[N] = { 0 };

    if (n == m) {

        if(check(q,p,n)){
            for(int i=0;i<n;i++){
            int a=p[i];
            p[i]=q[i];
            q[i]=a;}
            for (int i = 0; i < n; i++) {
            int g=f[i];
            f[i]+=q[i]-p[i];
            if (f[i] < 0) {
                f[i] = g+q[i] + 10-p[i];
                f[i + 1] -= 1;
            }

            } 
            int max = m > n ? m : n;


                   if(f[max-1]!=0)cout <<"-"<< f[max-1];
                      else cout<<"-";

                for (int i = 1; i <= check0(f,max); i++) {
                   cout << f[check0(f,max)-i];}
                          }
        else  {for (int i = 0; i < n; i++) {
            int g=f[i];
            f[i]+=q[i]-p[i];
            if (f[i] < 0) {
                f[i] = g+q[i] + 10-p[i];
                f[i + 1] -= 1;
            }

        } int max = m > n ? m : n;

            if(check_all_0(f,max))cout<<"0";
        else{if (f[max-1] != 0)cout << f[max-1];
    for (int i = 1; i <= check0(f,max); i++) {
        cout << f[check0(f,max)-i];}

        }
        }

    }


    else if (n > m) {
        for (int i = 0; i < m; i++) {
            int g=f[i];
            f[i] += q[i] - p[i];
            if (f[i] < 0) {
                f[i] =g + q[i] + 10-p[i];
                f[i + 1] -= 1;
            }
        }
        for (int j = 1; j <= n - m; j++) {
            f[m - 1 + j] += q[m - 1 + j];
            if (f[m - 1 + j] < 0) {
                f[m - 1 + j] = f[m - 1 + j] + 10;
                f[m + j] -= 1;
            }
        }
        int max = m > n ? m : n;


    if (f[max-1] != 0)cout << f[max-1];
    for (int i = 1; i < max; i++) {
        cout << f[max-i-1];
    }

    }
    else if (n < m) {
        for (int i = 0; i < n; i++) {
            int g=f[i];
            f[i] += p[i] -q[i];
            if (f[i] < 0) {
                f[i] = g+p[i]+ 10-q[i];
                f[i + 1] -= 1;
            }
        }
        for (int j = 1; j <= m - n; j++) {
            f[n - 1 + j] += p[n - 1 + j];  
            if (f[n - 1 + j] < 0) {
                f[n - 1 + j] = f[n - 1 + j] + 10;
                f[n + j] -= 1;
            }
        }
        int max = m > n ? m : n;

    if (f[max-1] != 0)cout <<"-"<< f[max-1];
    for (int i = 1; i < max; i++) {
        cout << f[max-i-1];
    }
    }

    }