SGU-135-Drawing Lines (simple mathematics !)

SGU-135-Drawing Lines (simple mathematics !)

SGU-135 Drawing Lines Time Limit:250 MS Memory Limit:4096KB 64bit IO Format:% I64d & % I64u Submit Status Description Little Johnny likes to draw a lot. A few days ago he painted lots of straight lines on his sheet of paper. then he counted in how many zones the sheet of paper was split by these lines. he noticed that this number is not always the same. for instance, if he draws2Lines, the sheet of paper cocould be split4,3Or even2(If the lines are identical) zones. since he is a very curious kid, he wowould like to know which is the maximum number of zones into which he can split the sheet of paper, if he drawsNLines. The sheet of paper is to be considered a very large (= infinite) rectangle. Input The input file will contain an integer number:N(0 <= N <= 65535). Output You shoshould output one integer: the maximum number of zones into which the sheet of paper can be split if Johnny drawsNLines. Sample Input #1 0 Sample Output #1 1 Sample Input #2 1 Sample Output #2 2 Author : Mugurel Ionut Andreica Resource : SSU: Online Contester Fall Contest #2 Date : Fall 2002 Source

It is also a mathematical problem ..

Rule: 1, 2, 4, 7, 11, 16... a (n) = n * (n + 1)/2 + 1; (n starts from 0)

AC code:

#include 
 
  #include 
  
   #include #include 
   
    #include 
    
     #include 
     
      using namespace std;int main(){int n;scanf("%d", &n);printf("%d\n", (int)((long long)n*(n+1)/2+1)); return 0;}