NC105 二分查找-II

https://www.nowcoder.com/practice/4f470d1d3b734f8aaf2afb014185b395

这题

func search(nums []int, target int) int {
    if nums == nil || len(nums) == 0 {
        return -1
    }

    var left, right = 0, len(nums) - 1
    for right >= left {
        mid := (right - left) / 2 + left
        if nums[mid] < target {
            left = mid + 1
        } else {
            right = mid - 1
        }
    }

    if nums[left] != target {
        return -1
    }

    return left
}

稍微改下（上面那种居然也能过...）：

func search(nums []int, target int) int {
    if nums == nil || len(nums) == 0 {
        return -1
    }

    var left, right, mid = 0, len(nums) - 1, 0
    for right >= left {
        mid = (right-left)/2 + left
        if nums[mid] < target {
            left = mid + 1
        } else if nums[mid] > target {
            right = mid - 1
        } else {
            // 找到最左
            for mid-1 >= 0 && nums[mid-1] == target {
                mid--
            }
            
            return mid
        }
    }

    return -1
}