Given a sorted integer array and a key, output its indices’ range.

getRange.java

/*
Given a sorted integer array and a key, output its indices’ range.

For example,
[5, 7, 7, 8, 8, 10] –> Given 8, outputs [3, 4]
*/
public class Untitled {
    // get a range of position of sorted array
    public int[] getRange(int[] input, int target) {
        int upper = getUpperBound(input, target);
        int lower = getLowerBound(input, target);
        int[] ret = new int[2];
        ret[0] = lower;
        ret[1] = upper;
        return ret;
    }
    // search upperbound of repeated target
    public int getUpperBound(int[] input, int target) {
        double left = 0;
        double right = input.length - 1;
        
        while(right >= left) {
            int mid = (int)Math.ceil((left + right)/2);
            if(input[mid] < target) {
                left = mid + 1;
            } else if(input[mid] > target) {
                right = mid - 1;
            } else {
                if(right != mid) {
                    left = mid;
                } else {
                    return mid;
                }
            }
        }
        
        return -1;
    }
    // search lowerbound of repeated target
    public int getLowerBound(int[] input, int target) {
        double left = 0;
        double right = input.length - 1;
        
        while(right >= left) {
            int mid = (int)Math.floor((left + right)/2.0);
            if(input[mid] < target) {
                left = mid + 1;
            } else if(input[mid] > target) {
                right = mid - 1;
            } else {
                if(left != mid) {
                    right = mid;
                } else {
                    return mid;
                }
            }
        }
        
        return -1;
    }
    public static void main(String[] args) {
        // Start typing your code here...
        System.out.println("Hello world!");
        int[] testInput = {5,7,7,8,8,8,8,8,10};
        Untitled test = new Untitled();
        int[] res = test.getRange(testInput, 4);
        System.out.println(res[0]);
        System.out.println(res[1]);   
    }
}