LeetCode进阶之路（ Search Insert Position）

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

题目：在一个有序数列中寻找目标值target，如果能找到，返回该值的位置；如果找不到，返回该插入的位置。

思路：用二分法找。

public int searchInsert(int[] nums, int target) {        int left = 0;        int right = nums.length - 1;        if(target < nums[left]) {//小于最小值，该插入0位置            return 0;        }                if(target > nums[right]) {//大于最大值，该插入最后一个位置            return nums.length;        }                while(left <= right) {            int mid = (right + left)/2;            if(nums[mid] == target) {//恰好是中间值，返回mid                return mid;            } else if(nums[mid] > target && nums[mid-1] < target) {//如果小于中间值，且大于前一位，返回mid                return mid;            } else if(nums[mid] < target && nums[mid+1] > target ) {//如果大于中间值，且小于后一位，返回mid+1                return mid+1;            }                        if(nums[mid] > target) {//继续二分发寻找合适的位置                right = mid - 1;            } else {                left = mid + 1;            }        }        return 0;    }

种一棵树最好的时间是十年前，其次是现在！