When submitting a solution in C++, please select either C++14 (GCC 6-32) or C++17 (GCC 7-32) as your compiler. ×

Evan_Shareef's blog

By Evan_Shareef, history, 3 years ago, In English

A pattern can be seen in the solution that the result will be equal to (n/2)*m . May be I am missing any mathematical concept behind this reason. Can anyone provide me the mathematical logic behind the solution? Why is this working?

Problem: https://vjudge.net/problem/LightOJ-1294

  • Vote: I like it
  • +3
  • Vote: I do not like it

| Write comment?
»
3 years ago, # |
Rev. 4   Vote: I like it +3 Vote: I do not like it

lets take an example for n=12 and m=3.

So 1,2,3,7,8,9 will have -ve sign and 4,5,6,10,11,12 will have positive sign

Now if you look carefully you can see that a n/2 pairs consisting of one +ve and one -ve numbers are formed such that their addition is equal to m

here,

4 — 1 = 3

5 — 2 = 3

6 — 3 = 3

10 — 7 = 3

11 — 8 = 3

12 — 9 = 3

Therefore n/2 pairs will be formed having sum of both numbers as m. Hence the answer is (n/2)*m

»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Why am i getting Runtime Error when using Fast IO but AC without that! WA AC