InterviewQuestions/src/package1/BinarySearch.java

Author: fishercoder1534

InterviewQuestions/src/package1/BinarySearch.java

@@ -0,0 +1,47 @@
+package package1;
+//Given a sorted array and a target, return the index of the target in this array, return -1 if not found.
+public class BinarySearch {
+
+	
+	//if not found in array, return -1;
+	public static int binarySearch(int[] nums, int target){
+		if(nums == null || nums.length == 0) return -1;
+		
+		int left = 0, right = nums.length-1;
+		if(nums[right] < target || nums[left] > target) return -1;
+		
+		while(left+1 < right){
+			int mid = left + (right-left)/2;
+			if(nums[mid] == target) return mid;
+			else if(nums[mid] > target){
+				right = mid;
+			} else {
+				left = mid;
+			}
+		}
+		if(nums[left] == target) return left;
+		else if(nums[right] == target) return right;
+		return -1;
+	}
+	
+	public static void main(String...strings){
+		
+		
+		
+		//test case 1:
+		int[] nums = new int[]{1,2,3,4,5,6,7,8,9};//lenght = 9, 9/2 = 4
+//		int target = 7;
+		
+//		test case 2:
+//		int target = 10;
+		
+		//test case 3:
+//		int target = -2;
+		
+//		int target = 1;
+		int target = 9;
+		
+		System.out.println(binarySearch(nums, target));
+		
+	}
+}