Toss strange coins

#[test]
fn t1() {
    let start = std::time::Instant::now();
    let val = Solution::probability_of_heads(vec![0.4], 1);
    let expected = 0.4;
    let pass = (val - expected).abs() < 1e-5;
    log_result!(pass, "t1", start, &expected, &val);
    assert!(pass);
}

#[test]
fn t2() {
    let start = std::time::Instant::now();
    let val = Solution::probability_of_heads(vec![0.5, 0.5, 0.5, 0.5, 0.5], 0);
    let expected = 0.03125;
    let pass = (val - expected).abs() < 1e-5;
    log_result!(pass, "t2", start, &expected, &val);
    assert!(pass);
}

#[test]
fn t3() {
    let start = std::time::Instant::now();
    let val = Solution::probability_of_heads(vec![1.0], 1);
    let expected = 1.0;
    let pass = (val - expected).abs() < 1e-5;
    log_result!(pass, "t3", start, &expected, &val);
    assert!(pass);
}

#[test]
fn t4() {
    let start = std::time::Instant::now();
    let val = Solution::probability_of_heads(vec![0.0, 0.0], 0);
    let expected = 1.0;
    let pass = (val - expected).abs() < 1e-5;
    log_result!(pass, "t4", start, &expected, &val);
    assert!(pass);
}

#[test]
fn t5() {
    let start = std::time::Instant::now();
    let val = Solution::probability_of_heads(vec![0.5, 0.5], 1);
    let expected = 0.5;
    let pass = (val - expected).abs() < 1e-5;
    log_result!(pass, "t5", start, &expected, &val);
    assert!(pass);
}