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#include <iostream>
#include <stack>
#include <string>
#include <algorithm>
#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); }
);
}
bool is_primitive(const std::string& token) {
return token == "+"
|| token == "-"
|| token == "*"
|| token == "."
|| token == "swp"
|| token == "dup"
|| token == "del";
}
void process(std::stack<int>& stack, const std::string& token) {
if ( token == "+" ) {
const int b = stack.top();
stack.pop();
const int a = stack.top();
stack.pop();
stack.push(a + b);
} else if ( token == "-" ) {
const int b = stack.top();
stack.pop();
const int a = stack.top();
stack.pop();
stack.push(a - b);
} else if ( token == "*" ) {
const int b = stack.top();
stack.pop();
const int a = stack.top();
stack.pop();
stack.push(a * b);
} else if ( token == "." ) {
std::cout << stack.top() << std::endl;
} else if ( token == "swp" ) {
const int b = stack.top();
stack.pop();
const int a = stack.top();
stack.pop();
stack.push(b);
stack.push(a);
} else if ( token == "dup" ) {
stack.push(stack.top());
} else if ( token == "del" ) {
stack.pop();
}
}
int main(int, char*[]) {
std::stack<int> stack;
std::string token;
while ( std::cin.good() ) {
if ( std::cin >> token ) {
if ( is_number(token) ) {
stack.push(std::atoi(token.c_str()));
} else if ( is_primitive(token) ) {
process(stack, token);
}
}
}
return 0;
}
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