public class Main {
    
    public static int binarySearch(int[] array, int key) {
        
        if(array == null || array.length == 0)
            return -1;
        int left = 0;
        int right = array.length - 1;
        int mid;
        while(left <= right) {
            
            mid = (left + right) / 2;
            if(array[mid] == key)
                return mid;
            if(array[mid] > key){
                
                right = mid - 1;
            }else {
                
                left = mid + 1;
            }
        }
        return -1;
    }
}