Added 1080B - Margarite and the best present.cpp

Author: vikashpatel24

1080B - Margarite and the best present.cpp

@@ -0,0 +1,64 @@
+//                                 ॐ नमः शिवाय
+#include<bits/stdc++.h>
+using namespace std;
+
+#define ll long long
+#define pb push_back
+#define ff first
+#define ss second
+#define mp make_pair
+ 
+// Code Written By: Vikash Patel
+// Codeforces Profile: https://codeforces.com/profile/vikashpatel
+
+int sumOdd(int n)
+{
+    int terms = (n + 1) / 2;
+    int sum = terms * terms;
+    return sum;
+}
+ 
+// Function to return the sum
+// of all odd numbers in range L and R
+int suminRange(int l, int r)
+{
+    return sumOdd(r) - sumOdd(l - 1);
+}
+
+int sumNatural(int n)
+{
+    int sum = (n * (n + 1));
+    return sum;
+}
+ 
+// Function to return sum
+// of even numbers in range L and R
+int sumEven(int l, int r)
+{
+    return sumNatural(r/2) - sumNatural((l-1) / 2);
+}
+
+//  https://www.geeksforgeeks.org/sum-of-all-even-numbers-in-range-l-and-r/
+//  https://www.geeksforgeeks.org/sum-of-all-odd-natural-numbers-in-range-l-and-r/
+
+int main()
+{
+    ios_base::sync_with_stdio(0);
+    cin.tie(0);
+    cout.tie(0);
+    
+    // #ifndef ONLINE_JUDGE
+    // freopen("input.txt", "r", stdin);
+    // freopen("/Users/vikash/Desktop/output.txt", "w", stdout);
+    // #endif
+    
+    int q;
+    cin>>q;
+    while(q--)
+    {
+       int l, r;
+       cin>>l>>r;
+       cout<<sumEven(l, r) - suminRange(l, r)<<endl;
+    }
+    return 0;
+}