34. Search for a Range

Given an array of integers sorted in ascending order, find the starting and ending position of a given target value.

Your algorithm’s runtime complexity must be in the order of O(log n).

If the target is not found in the array, return [-1, -1].

For example,
Given [5, 7, 7, 8, 8, 10] and target value 8,
return [3, 4].

public class Solution {  
    public int[] searchRange(int[] A, int target) {  
        int left = 0;  
        int right = A.length - 1;  

        int[] result = { -1, -1 };  

        while (left <= right) {  
            int mid = (left + right) / 2;  

            if (A[mid] > target) {  
                right = mid - 1;  
            } else if (A[mid] < target) {  
                left = mid + 1;  
            } else {  
                result[0] = mid;  
                result[1] = mid;  

                int i = mid - 1;  
                while (i >= 0 && A[i] == target) {  
                    result[0] = i;  
                    --i;  
                }  

                i = mid + 1;  
                while (i < A.length && A[i] == target) {  
                    result[1] = i;  
                    ++i;  
                }  

                break;  
            }  
        }   
        return result;  
    }  
}