LeetCode之Search Insert Position

1、问题

Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.

You may assume no duplicates in the array.

Here are few examples.
[1,3,5,6], 5 → 2
[1,3,5,6], 2 → 1
[1,3,5,6], 7 → 4
[1,3,5,6], 0 → 0

2、分析

我们这里用二分法，然后要注意的是，获取中间的下标是开始下标加末尾小标除以2，而不是末尾下标减去开始下标除以2，这里以后要注意。

3、代码实现

public static int searchInsert(int[] nums, int target) {
    int index = 0;
        if (nums == null || nums.length == 0) {
        return index;
        }
        if (target <= nums[0]) {
        return 0;
        }
        int length = nums.length;
        int start = 0;
        int end = length;
        while (start <= end) {
        int mid = (end + start) / 2;
        if (target < nums[mid]) {
        end = mid;
        } else if (target > nums[mid]){
        start = mid;
        } else  {
        return mid;
        }
        if (start - end == -1) {
        return start + 1;
        }
        }
        return index;
    }