10.25T1 模拟+栈

Description

 

 

 

 

很显然栈模拟一下就可以了

code：

#include<iostream>
#include<cstdio>
#include<stack>
#include<string>
#include<iomanip>
using namespace std;
stack<double>q;
double R[100005];
int main(){
    freopen("physic.in","r",stdin);
    freopen("physic.out","w",stdout);
    int n;
    cin>>n;
    for(int i=1;i<=n;i++)cin>>R[i];
    string S;
    cin>>S; 
    for(int i=0;i<S.size();i++){
        if(S[i]=='('){q.push(-1);}
        if(S[i]=='R'){q.push(R[S[i+1]-'0']);i++;}
        if(S[i]=='|'){q.push(-2);}
        if(S[i]=='-'){q.push(-3);}
        if(S[i]==')'){
            double now=q.top();
            q.pop();
            if(q.top()==-2)now=1/now;
            int flag=0;
            while(q.top()!=-1){
                if(q.top()==-3){
                    q.pop();
                    now+=q.top();
                    q.pop();
                }
                if(q.top()==-2){
                    flag=1;
                    q.pop();
                    now+=1.0/q.top();
                    q.pop();
                }
            }
            q.pop();
            if(!flag)
            q.push(now);
            else{
                q.push(1.0/now);
            }
        }
    }
    cout<<fixed<<setprecision(4)<<q.top();
    return 0;
}
/*
8
2.3 4.5 8.1 4.0 5.6 7.7 8.8 9.1
(((R1-(R2|R3)-(R4|R5))|(R1-(R2|R3)-(R4|R5)))|(R8-R7-R6))
*/

over