Binary Search

binarySearch.cpp

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+// C++ program to implement recursive Binary Search
+#include <bits/stdc++.h>
+using namespace std;
+
+// A recursive binary search function. It returns
+// location of x in given array arr[l..r] is present,
+// otherwise -1
+int binarySearch(int arr[], int l, int r, int x)
+{
+	if (r >= l) {
+		int mid = l + (r - l) / 2;
+
+		// If the element is present at the middle
+		// itself
+		if (arr[mid] == x)
+			return mid;
+
+		// If element is smaller than mid, then
+		// it can only be present in left subarray
+		if (arr[mid] > x)
+			return binarySearch(arr, l, mid - 1, x);
+
+		// Else the element can only be present
+		// in right subarray
+		return binarySearch(arr, mid + 1, r, x);
+	}
+
+	// We reach here when element is not
+	// present in array
+	return -1;
+}
+
+int main(void)
+{
+	int arr[] = { 2, 3, 4, 10, 40 };
+	int x = 10;
+	int n = sizeof(arr) / sizeof(arr[0]);
+	int result = binarySearch(arr, 0, n - 1, x);
+	(result == -1)
+		? cout << "Element is not present in array"
+		: cout << "Element is present at index " << result;
+	return 0;
+}