binary search templates

BinarySearch1.cs

public int BinarySearch1(int[] nums, int target){
    if (nums == null || nums.Length == 0) {
        return -1;
    }

    int lo = 0, hi = nums.Length - 1;
    while (lo <= hi) {
        // Prevent (lo + hi) overflow
        int mid = lo + (hi - lo) / 2;
        if (nums[mid] == target) {
            return mid;
        } else if (nums[mid] < target) {
            lo = mid + 1;
        } else {
            hi = mid - 1;
        }
    }

    // End Condition: left > hi
    return -1;
}

BinarySearch2.cs

public int BinarySearch2(int[] nums, int target) {
    if (nums == null || nums.Length == 0) {
        return -1;
    }

    int lo = 0, hi = nums.Length;
    while (lo < hi) {
        // Prevent (lo + hi) overflow
        int mid = lo + (hi - lo) / 2;
        if (nums[mid] == target) {
            return mid;
        } else if(nums[mid] < target) {
            lo = mid + 1;
        } else {
            hi = mid;
        }
    }

    // Post-processing:
    // End Condition: lo == hi
    if (lo != nums.Length && nums[lo] == target) {
        return lo;
    }
    
    return -1;
}

BinarySearch3.cs

public int BinarySearch3(int[] nums, int target) {
    if (nums == null || nums.Length == 0) {
        return -1;
    }

    int lo = 0, hi = nums.Length - 1;
    while (lo + 1 < hi) {
        // Prevent (lo + hi) overflow
        int mid = lo + (hi - lo) / 2;
        if (nums[mid] == target) {
            return mid;
        } else if (nums[mid] < target) {
            lo = mid;
        } else {
            hi = mid;
        }
    }

    // Post-processing:
    // End Condition: lo + 1 == hi
    if (nums[lo] == target) return lo;
    if (nums[hi] == target) return hi;
    return -1;
}