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#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;
}
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