rust "binary_search" return type -> choose uszie or i32 ?

[XIAOZHUXUEJAVA]

I think the binary search in Rust could be written like this:

pub fn binary_search(nums: &[i32], target: i32) -> Option<usize> {
        let mut low = 0;
        let mut high = nums.len();
        while low < high {
            let mid = (high - low) / 2 + low;
            match target.cmp(&nums[mid]) {
                std::cmp::Ordering::Equal => return Some(mid),
                std::cmp::Ordering::Less => high = mid,
                std::cmp::Ordering::Greater => low = mid + 1,
            }
        }
        None
}

This is more in line with Rust's language features， maybe

[krahets]

@sjinzh @xBLACKICEx

[krahets]

Simplicity is one of the principles of this book.

This looks like a language syntax sugar that doesn't suppress the if ... else ... in performance or simplicity.

            match target.cmp(&nums[mid]) {
                std::cmp::Ordering::Equal => return Some(mid),
                std::cmp::Ordering::Less => high = mid,
                std::cmp::Ordering::Greater => low = mid + 1,
            }

Using usize is more formal and with greater adaptivity. However, it is not vital for the subject of data structure and algorithms.

[XIAOZHUXUEJAVA]

The code use of while i <= j and j = m - 1 in the code may lead to boundary issues (left inclusive, right inclusive interval).

In Rust, array indices must be of non-negative integer type usize. This means that if we want to access an element of an array, we must provide a non-negative integer index, which means that the code will fail when the target value is smaller than all array elements.

Of course, my programming level is not high, and my analysis may not be accurate.

Of course, you are not wrong that data structures and algorithms are indeed largely language-independent, but in my view, there is a problem with this code. If you do not think so, you can ignore this.

    #[test]
    fn test_binary_search() {
        let nums = [2, 3, 4, 7, 9];
        assert_eq!(-1, BinarySearch::binary_search_i(&nums, 1));
    }

For instance:

[krahets]

It is designed to return -1 when not finding the target. I believe it is fine to return i32 type here.

[krahets]

@night-cruise Could you please track the issue, thanks!