10.25T1 模拟+栈

Description

很显然栈模拟一下就可以了
code：
 1 #include<iostream>
 2 #include<cstdio>
 3 #include<stack>
 4 #include<string>
 5 #include<iomanip>
 6 using namespace std;
 7 stack<double>q;
 8 double R[100005];
 9 int main(){
10     freopen("physic.in","r",stdin);
11     freopen("physic.out","w",stdout);
12     int n;
13     cin>>n;
14     for(int i=1;i<=n;i++)cin>>R[i];
15     string S;
16     cin>>S; 
17     for(int i=0;i<S.size();i++){
18         if(S[i]=='('){q.push(-1);}
19         if(S[i]=='R'){q.push(R[S[i+1]-'0']);i++;}
20         if(S[i]=='|'){q.push(-2);}
21         if(S[i]=='-'){q.push(-3);}
22         if(S[i]==')'){
23             double now=q.top();
24             q.pop();
25             if(q.top()==-2)now=1/now;
26             int flag=0;
27             while(q.top()!=-1){
28                 if(q.top()==-3){
29                     q.pop();
30                     now+=q.top();
31                     q.pop();
32                 }
33                 if(q.top()==-2){
34                     flag=1;
35                     q.pop();
36                     now+=1.0/q.top();
37                     q.pop();
38                 }
39             }
40             q.pop();
41             if(!flag)
42             q.push(now);
43             else{
44                 q.push(1.0/now);
45             }
46         }
47     }
48     cout<<fixed<<setprecision(4)<<q.top();
49     return 0;
50 }
51 /*
52 8
53 2.3 4.5 8.1 4.0 5.6 7.7 8.8 9.1
54 (((R1-(R2|R3)-(R4|R5))|(R1-(R2|R3)-(R4|R5)))|(R8-R7-R6))
55 */
over