change implementation to binary-search

searching.cpp

 #include "main.cpp"
 bool search_custom(vector<int> a,int num){
-    for(int i=0;i<a.size();i++){
-        if(a[i]==num)
-            return true;
-    }
-    return false;
+       int n=a.size();
+ int i=0,f=n-1;
+ while(true)
+	{
+	 if(i==f) 
+		{
+		 if(a[i]==num) return true;
+		 return false;
+		}
+	 if(f==i+1)
+		{
+		 if(a[i]==num) return true;
+		 if(a[f]==num) return false;
+		 return false;
+		}
+	 int c=(i+f)/2;
+	 if(a[c]==num) return true;
+	 if(a[c]>num)
+		{
+		 f=c-1;
+		}
+	 else
+		{
+		 i=c+1;
+		}
+	}
+ return false;
 }