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public class Main {
public static final int NOT_FOUND = -1;
public static int binarySearch(Comparable[] a, Comparable x) {
return binarySearch(a, x, 0, a.length - 1);
}
private static int binarySearch(Comparable[] a, Comparable x, int low, int high) {
if (low > high)
return NOT_FOUND;
int mid = (low + high) / 2;
if (a[mid].compareTo(x) < 0)
return binarySearch(a, x, mid + 1, high);
else if (a[mid].compareTo(x) > 0)
return binarySearch(a, x, low, mid - 1);
else
return mid;
}
public static void main(String[] args) {
int SIZE = 8;
Comparable[] a = new Integer[SIZE];
for (int i = 0; i < SIZE; i++)
a[i] = new Integer(i * 2);
for (int i = 0; i < SIZE * 2; i++)
System.out.println("Found " + i + " at " + binarySearch(a, new Integer(i)));
}
}
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