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Ingy döt Net 2023-07-01 11:58:00 -04:00
parent 7387c8f97b
commit cb5bb5e222
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54
Task/Parsing-RPN-calculator-algorithm/Rust/parsing-rpn-calculator-algorithm.rust Normal file
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fn rpn(text: &str) -> f64 {
let tokens = text.split_whitespace();
let mut stack: Vec<f64> = vec![];
println!("input operation stack");
for token in tokens {
print!("{:^5} ", token);
match token.parse() {
Ok(num) => {
stack.push(num);
println!("push {:?}", stack);
}
Err(_) => {
match token {
"+" => {
let b = stack.pop().expect("missing first operand");
let a = stack.pop().expect("missing second operand");
stack.push(a + b);
}
"-" => {
let b = stack.pop().expect("missing first operand");
let a = stack.pop().expect("missing second operand");
stack.push(a - b);
}
"*" => {
let b = stack.pop().expect("missing first operand");
let a = stack.pop().expect("missing second operand");
stack.push(a * b);
}
"/" => {
let b = stack.pop().expect("missing first operand");
let a = stack.pop().expect("missing second operand");
stack.push(a / b);
}
"^" => {
let b = stack.pop().expect("missing first operand");
let a = stack.pop().expect("missing second operand");
stack.push(a.powf(b));
}
_ => panic!("unknown operator {}", token),
}
println!("calculate {:?}", stack);
}
}
}
stack.pop().unwrap_or(0.0)
}
fn main() {
let text = "3 4 2 * 1 5 - 2 3 ^ ^ / +";
println!("\nresult: {}", rpn(text));
}