35. 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.

Example 1:

Input: [1,3,5,6], 5
Output: 2

Example 2:

Input: [1,3,5,6], 2
Output: 1

Example 3:

Input: [1,3,5,6], 7
Output: 4

Example 4:

Input: [1,3,5,6], 0
Output: 0

Solution

class Solution {
    public int searchInsert(int[] nums, int target) {
        int len = nums.length;
        int start = 0;
        int end = len - 1;
        //Shall check start == end case, since the start/end might be unchecked
        //for ex: 2,4,5 target = 3, start = 0, end = 0(ie.mid-1), 
        //however the insert index shall be 1
        //for ex: 2,4,7 target = 8, start = 2(ie.mid+1), end = 2, 
        //however the insert index shall be 3
        while(start <= end){
            //For avoid start+end is overflowed
            int mid = start + (end - start)/2;
            if(nums[mid] == target)
                return mid;
            else if (nums[mid] < target){
                start = mid + 1;
            }
            else{
                //mid > target
                end = mid - 1;
            }
        }
        return start;
    }
}