chore(C): added binary search (#257)

algorithms/C/README.md

@@ -22,3 +22,8 @@
 - [Count Words](strings/count-words.c)
 - [Palindrome](strings/palindrome.c)
 - [Permutation of String](string/Permutation-of-String.c)
+
+## Searching
+- [Binary Search](searching/Binary-search.c)
+
+  

algorithms/C/searching/Binary-search.c

@@ -0,0 +1,74 @@
+/*
+Problem: Search data using Binary Search
+Binary Search: It is a way to search data in efficient time.It
+works by repeatedly dividing in half the portion of the
+list that could contain the item, until you have narrowed down
+the possible locations to just one.
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+
+//Function to search data using binary search
+int binary_search(int *arr,int size,int to_search)
+{
+    //initialize start as 0 and end as size-1
+    int start=0,end=size-1,mid;
+    //until start is less than or equal to end run the loop
+    while(start<=end)
+    {
+       //every time assign start+((end-start)/2)(middle element of the current array) in mid
+       mid=start+((end-start)/2);
+       // if the data found in middle of the array then return the index
+       if(arr[mid]==to_search)
+            return mid;
+        /* if the middle index value of array is greater than to search
+         the data to search is less than middle element of current element so end should be
+         assign less than middle means mid-1 */
+        else if(arr[mid]>to_search)
+            end=mid-1;
+        /* if else condition runs that means the data is greater than the middle element of
+        current array so the start variable should have mid+1 index number */
+        else
+            start=mid+1;
+    }
+    // if the data not found till the loop run that means data is not present in given array
+    return -1;
+}
+//driver code
+int main()
+{
+    int size,*arr,i,to_search,result;
+    printf("Enter size: ");
+    //taking size
+    scanf("%d",&size);
+    //dynamically allocating memory and assigning the base address in arr
+    arr=(int*)malloc(sizeof(int)*size);
+    for(i=0;i<size;i++)
+    scanf("%d",&arr[i]);
+    printf("Enter a number to search: ");
+    //taking the data to search
+    scanf("%d",&to_search);
+    // calling binary_search to find the element index or -1 if not present and assign it to result
+    result=binary_search(arr,size,to_search);
+    if(result==-1)
+        printf("Data Not Found");
+    else
+        printf("Data Found at index no: %d",result);
+    return 0;
+}
+/*
+Case 1:
+Input: Enter size: 5
+       1  2   3   4   5
+       Enter a number to search: -1
+Output: Data Not Found
+
+Case 2:
+Input: Enter size: 5
+       2  5   9   110   112
+       Enter a number to search: 110
+Output: Data Found at index no: 3
+
+Time complexity: O(log N) where N is the size of array
+*/