1 #include<bits/stdc++.h>
2 using namespace std;
3 /**
4 * 仿LISP运算
5 * 模拟(sub (mul 2 4) (div 9 3))
6 * @return
7 */
8
9 int main() {
10 int mark = 0;
11 int num1,num2;
12 string str;
13 stack<int> numStatck;
14 stack<string> operStack;
15
16 getline(cin,str);
17 for(int i = 0; i < str.length() ; i++)
18 {
19 char c = str[i];
20 cout<<c<<" ";
21 if(c == '(') {
22 operStack.push(str.substr(i+1,3));
23 i += 4;
24 mark = i + 1;
25 } else if(c == ')') {
26 if(mark < i) {
27 //stoi string --> int
28 numStatck.push(stoi(str.substr(mark,i-mark)));
29
30 i++;
31 mark = i + 1;
32 }
33 num1 = numStatck.top();
34 numStatck.pop();
35 num2 = numStatck.top();
36 numStatck.pop();
37 string ex = operStack.top();
38 operStack.pop();
39
40 if(ex == "add")
41 numStatck.push(num1+num2);
42 else if(ex == "sub")
43 numStatck.push(num1-num2);
44 else if (ex == "mul")
45 numStatck.push(num1*num2);
46 else if( ex == "div")
47 if(num2 == 0) cout <<"ERROR"<<endl;
48 else
49 numStatck.push(num2/num1);
50
51 } else {
52 if(c == ' ') {
53 if(mark < i ) {
54 numStatck.push(stoi(str.substr(mark,i-mark)));
55 mark = i + 1;
56 }
57 }
58 }
59 }
60 cout<<"结果：";
61 cout<<numStatck.top()<<endl;
62 return 0;
63 }
