后缀表达式的值
1 #include<iostream>
2 #include<cstring>
3 #include<stack>
4 using namespace std;
5 typedef long long ll;
6 ll t;
7 stack<ll> sta;
8 ll cal(ll t1,ll t2,char c){
9 ll ans;
10 if(c=='+')ans=t1+t2;
11 else if(c=='-')ans=t2-t1;
12 else if(c=='*')ans=t1*t2;
13 else ans=t2/t1;
14 return ans;
15 }
16 int main(){
17 string s;
18 while(cin>>s){
19 if(s[0]>='0'&&s[0]<='9'){
20 t=0;
21 for(int i=0;i<s.length();i++)
22 t=t*10+s[i]-'0';
23 sta.push(t);
24 }else{
25 for(int i=0;i<s.length()-1;i++){
26 ll t1=sta.top(),t2;
27 sta.pop();
28 t2=sta.top();
29 sta.pop();
30 sta.push(cal(t1,t2,s[i]));
31 }
32 break;
33 }
34 }
35 cout<<sta.top();
36 return 0;
37 }
