Add readmefile

Binary_search/README.md

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+BINARY ALGORITHM
+This algorithm help the user to search a particular element present in an array(using the index of element present in an array)
+**How the Algorithm Works**
+1. Find the middle element
+2. If middle element equal to searched value algorithm stops:
+   otherwise there are two cases:
+   2.1 search the value is less than that of the middle element.Here, 
+       the algorithm go to the step 1 for the part of the array that before middle element
+   2.2 search the value is greater than that of the middle element.And here, 
+       the algorithm go to the step 1 for the part of the array that after middle element  

Binary_search/main.cpp

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+#include <iostream> 
+using namespace std;  
+int binarySearch(int arr[], int l, int r, int x) 
+{ 
+    if (r >= l) 
+    { 
+        int mid = l + (r - l) / 2;
+        if (arr[mid] == x) 
+            return mid; 
+        if (arr[mid] > x) 
+            return binarySearch(arr, l, mid - 1, x); 
+        return binarySearch(arr, mid + 1, r, x); 
+    } 
+    return -1; 
+} 
+
+int main(void) 
+{ 
+    int arr[] = { 24, 33, 4, 130, 41 }; 
+    int x = 4; 
+    int n = sizeof(arr) / sizeof(arr[0]); 
+    int result = binarySearch(arr, 0, n - 1, x); 
+    (result == -1) ? cout << "No such Element in array"
+                   : cout << "Element is present at index " << result; 
+    return 0; 
+}