Search Insert Position

Total Accepted: 100201 Total Submissions: 269978 Difficulty: Medium
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

思路

• 典型binary search
• 注意一下最后的位置,可能小于start,也可能大于end

public class Solution {
    public int searchInsert(int[] nums, int target) {
        if (nums == null || nums.length == 0) {
            return -1;
        }

        int len = nums.length;
        int start = 0;
        int end = len - 1;
        while (start + 1 < end) {
            int mid = start + (end - start) / 2;
            if (nums[mid] == target) {
                return mid;
            }
            else if (nums[mid] > target) {
                end = mid;
            }
            else {
                start = mid;
            }
        }

        if (target > nums[end]) {
            return end + 1;
        }

        if (target == nums[start] || target < nums[start]) {
            return start;
        } else {
            return end;
        }

    }
}