Create Binarysearch.cpp

c++/Binarysearch.cpp

@@ -0,0 +1,42 @@
+#include <iostream>
+//time complexityy if O(log n)
+using namespace std;
+int binarysearch(int arr[] , int size , int key){
+    int start =0;
+    int end=size-1;
+    int mid=(start+end)/2;
+    //also;
+    //mid== start + (end-start)/2
+    while(start<=end){
+        if(arr[mid]==key){
+            return mid;
+        }
+        //right bala part par jayo 
+        if(key>arr[mid]){
+            //right part
+            start=mid+1;
+        }
+        //left bale part par jayo
+        else if(key<arr[mid]){
+            end=mid-1;
+        }
+        //mid ka value bhi update kar do
+        mid=(start+end)/2;
+    }
+    // if key is not present in the array the we return -1
+
+    return -1;
+}
+int main()
+{
+    int even[]={2,4,6,8,12,18};
+    int odd[]={3,8,11,14,16};
+
+    int index1=binarysearch(even , 6,12);
+    cout<<"index of the key in the array is  ="<<index1<<endl;
+
+    int index2=binarysearch(odd , 5,10);
+    cout<<"index of the key in the array is  ="<<index2<<endl;
+
+    return 0;
+}