1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
|
#include <iostream>
#include <stack>
#include <string>
#include <algorithm>
#include <unordered_map>
#include <functional>
#include <cctype>
#include <cstdlib>
bool is_number(const std::string& token) {
return std::all_of(
token.begin(),
token.end(),
[](char c) { return std::isdigit(c); }
);
}
int main(int, char*[]) {
std::stack<int> stack;
std::string token;
std::unordered_map<std::string, std::function<void(void)>> builtin{
{
"+", [&stack]() {
const int b = stack.top();
stack.pop();
const int a = stack.top();
stack.pop();
stack.push(a + b);
}
},
{
"-", [&stack]() {
const int b = stack.top();
stack.pop();
const int a = stack.top();
stack.pop();
stack.push(a - b);
}
},
{
"*", [&stack]() {
const int b = stack.top();
stack.pop();
const int a = stack.top();
stack.pop();
stack.push(a * b);
}
},
{
".", [&stack]() {
std::cout << stack.top() << std::endl;
}
},
{
"swp", [&stack]() {
const int b = stack.top();
stack.pop();
const int a = stack.top();
stack.pop();
stack.push(b);
stack.push(a);
}
},
{
"dup", [&stack]() {
stack.push(stack.top());
}
},
{
"del", [&stack]() {
stack.pop();
}
}
};
while ( std::cin.good() ) {
if ( std::cin >> token ) {
if ( is_number(token) ) {
stack.push(std::atoi(token.c_str()));
} else {
const auto& impl = builtin.find(token);
if ( impl != builtin.end() ) {
impl->second();
}
}
}
}
return 0;
}
|
