【杭电多校2020】1002.Little Rabbit‘s Equation

题目链接

思路：

暴力模拟.

代码：

#include<bits/stdc++.h>
#define int long long
#define IOS ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
const int N=1e5+3;
const int M=2e4+5;
const double eps=1e-8;
const int mod=998244353;
const int inf=0x7fffffff;
const double pi=3.1415926;
using namespace std;
bool solve(string s,int r)
{
    int num1=0,num2=0,num3=0,fg=0;
    char op;
    for(auto i:s)
    {
        if(i>='0'&&i<='9')
        {
            if(fg==0)
                num1=num1*r+(i-'0');
            else if(fg==1)
                num2=num2*r+(i-'0');
            else if(fg==2)
                num3=num3*r+(i-'0');
            if(i-'0'>=r)
                return false;
        }
        else if(i>='A'&&i<='F')
        {
            if(fg==0)
                num1=num1*r+(i-'A')+10;
            else if(fg==1)
                num2=num2*r+(i-'A')+10;
            else if(fg==2)
                num3=num3*r+(i-'A')+10;
            if(i-'A'+10>=r)
                return false;
        }
        else if(i=='+'||i=='-'||i=='*'||i=='/')
        {
            op=i;
            fg=1;
        }
        else if(i=='=')
            fg=2;
    }
    if(op=='+')
        if(num1+num2==num3)
            return true;
    if(op=='-')
        if(num1-num2==num3)
            return true;
    if(op=='*')
        if(num1*num2==num3)
            return true;
    if(op=='/')
        if((double)(num1*1.0/(1.0*num2))==(double)num3)
            return true;
    return false;
}
signed main()
{
    string s;
    while(cin>>s)
    {
        int ans=-1;
        for(int i=2;i<=16;i++)
        {
            if(solve(s,i))
            {
                ans=i;
                break;
            }
        }
        cout<<ans<<endl;
    }
    return 0;
}