Binary Search

binary_search.java

public class BinarySearch {
	// Find first target in array
	public int binarySearch(int[] arr, int target){
		if (arr.length == 0){
			return -1;
		}
		
		int start = 0 ;
		int end = arr.length - 1;
		int mid;

		while (start + 1 < end){
			mid = start + (end - start) / 2;
			if (arr[mid] < target){
				start = mid;
			}else{
				end = mid;
			}
		}
		if (arr[start] == target){
			return start;
		}
		if (arr[end] == target){
			return end;
		}
		return -1;
	}
}