Search Insert Position

LintCode-60.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

[1,3,5,6], 5 → 2

[1,3,5,6], 2 → 1

[1,3,5,6], 7 → 4

[1,3,5,6], 0 → 0

Challenge

O(log(n)) time

public class Solution {
    /** 
     * param A : an integer sorted array
     * param target :  an integer to be inserted
     * return : an integer
     */
    public int searchInsert(int[] A, int target) {
        if (A == null || A.length == 0) {
            return 0;
        }
        
        int low = 0;
        int high = A.length - 1;
        
        while (low + 1 < high) {
            int middle = low + (high - low) / 2;
            
            if (A[middle] == target) {
                return middle;
            } else if (A[middle] > target) {
                high = middle;
            } else {
                low = middle;
            }
        }
        
        if (A[low] >= target) {
            return low;
        } else if (A[high] >= target) {
            return high;
        } else {
            return high + 1;
        }
    }
}

Hope this helps,
Michael