Added Problem A CodeForces Round 638

Author: 0xsanchit

Codeforces_Contests/Round_638_Div_2/A.cpp

@@ -0,0 +1,49 @@
+/**************************************************************************
+ *  $Id$
+ *  File:	
+ *
+ *  Purpose:	
+ *
+ *  Author:	Sanchit Gupta (CS19B071)
+ *
+ *  Created:    
+ *
+ *  Last modified:  
+ *
+ *  Bugs:	
+ *
+ *  Change Log:	
+ *
+ * While(!(succeed==try());
+ **************************************************************************/
+ #include<iostream>
+ #include<bits/stdc++.h>
+ 
+ using namespace std;
+ 
+ int main()
+ {
+     int t;
+     cin>>t;
+     while(t--)
+     {
+        long long int n;
+        cin>>n;
+        long long int sum1=0,sum2=0;
+        long long int current=2,i=1;
+        while(i<(n/2))
+        {
+            sum1=sum1+current;
+            current=current*2;
+            i++;
+        }
+        while(i<n)
+        {
+            sum2=sum2+current;
+            current=current*2;
+            i++;
+        }
+        sum1=sum1+current;
+        cout<<abs(sum1-sum2)<<endl;
+     }
+ }