need help with day 7 part 1 of adventofcode

    
use std::fs;

fn calculate(answer: &i32, numbers: &mut Vec<i32>) -> bool {
    if numbers.len() >= 2 {
    let tmp1 = numbers[0];
    let tmp2 = numbers[1];
    numbers.remove(0);
    numbers.remove(0);

    numbers.insert(0, tmp1 * tmp2);

    if calculate(answer, numbers) == true {
        return true;
    } else {
        numbers.remove(0);
        numbers.insert(0, tmp1 + tmp2);
        if calculate(answer, numbers) == true {
        return true;
        } else {
        return false;
        }
    }
    } else {
    if *answer == numbers[0] {
        println!("> {} true", numbers[0]);
        return true;
    } else {
        println!("> {} false", numbers[0]);
        return false;
    }
    }
}

fn main() {
    let contents = fs::read_to_string("sample.txt")
        .expect("Should have been able to read the file");

    for line in contents.lines() {
    let tmp = line.split(":").collect::<Vec<&str>>();
    let answer = tmp[0].to_string().parse::<i32>().unwrap();
    println!("{:?}", answer);
    let numbers_str = tmp[1].split(" ");
    let mut numbers: Vec<i32> = Vec::new();
    for num in numbers_str {
        if num.len() == 0 {
        continue;
        }
        numbers.push(num.parse::<i32>().unwrap());
    }
    println!("{:?}", numbers);
    if calculate(&answer, &mut numbers) == true {
        println!("it's true");
    }
    }
}