DataStructure & Algorithms

BinarySearch.java

public static int binarySearch(int[] A, int target){
		
		if (A.length ==0 || A == null ) {
			return -1;
		}
		
		int start = 0;
		int end = A.length - 1;
		int mid;
		
		if (target == A[start]) {
			return start;
		}
		
		if (target == A[end]) {
			return end;
		}
		
		while(start + 1 < end) {
			mid = start + (end - start) / 2;
			
			System.out.println("Before" + start + " " + end + " " + mid );
			
			if (target == A[mid]){
				return mid;
			} else if (target < A[mid]) {
				end = mid;
			} else if (target > A[mid]) {
				start = mid;
			}
			
			System.out.println("After" + start + " " + end + " " + mid );
			
		}
		
		return -1;	
	}