Single number

#[test]
fn test_larger_array() {
    let start = std::time::Instant::now();
    let val = Solution::single_number(vec![7, 3, 5, 4, 5, 3, 4]);
    let expected = 7;
    log_result!(val == expected, "test_larger_array", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn test_single_element() {
    let start = std::time::Instant::now();
    let val = Solution::single_number(vec![1]);
    let expected = 1;
    log_result!(val == expected, "test_single_element", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn test_single_number_1() {
    let start = std::time::Instant::now();
    let val = Solution::single_number(vec![2, 2, 1]);
    let expected = 1;
    log_result!(val == expected, "test_single_number_1", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn test_single_number_4() {
    let start = std::time::Instant::now();
    let val = Solution::single_number(vec![4, 1, 2, 1, 2]);
    let expected = 4;
    log_result!(val == expected, "test_single_number_4", start, &expected, &val);
    assert_eq!(val, expected);
}