Rearrange words in a sentence

#[test]
fn t1() {
    let start = std::time::Instant::now();
    let val = Solution::arrange_words("Leetcode is cool".to_string());
    let expected = "Is cool leetcode".to_string();
    log_result!(val == expected, "t1", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t2() {
    let start = std::time::Instant::now();
    let val = Solution::arrange_words("Keep calm and code on".to_string());
    let expected = "On and keep calm code".to_string();
    log_result!(val == expected, "t2", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t3() {
    let start = std::time::Instant::now();
    let val = Solution::arrange_words("To be or not to be".to_string());
    let expected = "To be or to be not".to_string();
    log_result!(val == expected, "t3", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t4() {
    let start = std::time::Instant::now();
    let val = Solution::arrange_words("Hello".to_string());
    let expected = "Hello".to_string();
    log_result!(val == expected, "t4", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t5() {
    let start = std::time::Instant::now();
    let val = Solution::arrange_words("All we know is that we know nothing".to_string());
    let expected = "We is we all know that know nothing".to_string();
    log_result!(val == expected, "t5", start, &expected, &val);
    assert_eq!(val, expected);
}