[leetcode] Search Insert Position

思路：其实就是用普通的二分查找，只不过在找不到该数时，left下标就是应该插入的位置，返回该下标即可。

Java代码如下：

    public int searchInsert(int[] nums, int target) {
        int left = 0;
        int right = nums.length - 1;
        while (left <= right) {
            int mid = (left + right)/2;
            if (nums[mid] == target) {
                return mid;
            }
            else if (nums[mid] > target) {
                right = mid - 1;
            }
            else {
                left = mid + 1;
            }
        }
        return left;
    }