import java.util.*;
class Entry {
int key;
int value;
public Entry(int key, int value) {
this.key = key;
this.value = value;
}
}
class KClosestElements {
public static List<Integer> findClosestElements(int[] arr, int K, Integer X) {
int index = binarySearch(arr, X);
int low = index - K, high = index + K;
low = Math.max(low, 0); // 'low' should not be less than zero
high = Math.min(high, arr.length - 1); // 'high' should not be greater the size of the array
PriorityQueue<Entry> minHeap = new PriorityQueue<>((n1, n2) -> n1.key - n2.key);
// add all candidate elements to the min heap, sorted by their absolute difference from 'X'
for (int i = low; i <= high; i++)
minHeap.add(new Entry(Math.abs(arr[i] - X), i));
// we need the top 'K' elements having smallest difference from 'X'
List<Integer> result = new ArrayList<>();
for (int i = 0; i < K; i++)
result.add(arr[minHeap.poll().value]);
Collections.sort(result);
return result;
}
private static int binarySearch(int[] arr, int target) {
int low = 0;
int high = arr.length - 1;
while (low <= high) {
int mid = low + (high - low) / 2;
if (arr[mid] == target)
return mid;
if (arr[mid] < target) {
low = mid + 1;
} else {
high = mid - 1;
}
}
if (low > 0) {
return low - 1;
}
return low;
}
public static void main(String[] args) {
List<Integer> result = KClosestElements.findClosestElements(new int[] { 5, 6, 7, 8, 9 }, 3, 7);
System.out.println("'K' closest numbers to 'X' are: " + result);
result = KClosestElements.findClosestElements(new int[] { 2, 4, 5, 6, 9 }, 3, 6);
System.out.println("'K' closest numbers to 'X' are: " + result);
result = KClosestElements.findClosestElements(new int[] { 2, 4, 5, 6, 9 }, 3, 10);
System.out.println("'K' closest numbers to 'X' are: " + result);
}
}
The above solution fails on these inputs
arr = [0,0,1,2,3,3,4,7,7,8]
k = 3
x = 5
Expected: [3,3,4]
What this solution returns? : [3,4,7]