Merge pull request #57 from ragupathi09/master

C++ Binary search

Author: kishanrajput23

C++/Binary_search.cpp

@@ -0,0 +1,51 @@
+#include<iostream>
+using namespace std;
+// recursive function for binary search
+/* if match found then return index of search key
+   else return -1 */
+int binarySearch(int arr[], int low, int high, int key) {
+  if (high >= low) {
+    // find middle index
+    int mid = low + (high - low) / 2; 
+     
+    // find middle term and compare
+    if (arr[mid] == key) return mid; // key found 
+     
+    // If key is smaller than middle term, then 
+    // it can only be present in left subarray 
+    if (arr[mid] > key) 
+      return binarySearch(arr, low, mid - 1, key); 
+    
+    // Else the key can only be present 
+    // in right subarray 
+    return binarySearch(arr, mid + 1, high, key); 
+  } 
+     
+  // key not found
+  return -1; 
+}
+
+// main function
+int main()
+{
+  int array[] = {10, 20, 30, 40, 50, 60, 70, 80, 90, 100};
+  int key = 0;
+
+  // take input for the search key
+  cout << "Enter Search Element: ";
+  cin >> key;
+
+  // find the size array
+  int size = sizeof(array)/sizeof(array[0]);
+
+  // search key
+  int index = binarySearch(array, 0, size, key);
+  
+  // display result
+  if(index == -1)
+    cout << key << " Not Found" << endl;
+  else
+    cout << key << " Found at Index = " << index << endl;
+
+  return 0;
+}