fork download 
  1. import math
  2.  
  3. for _ in range(input()):
  4.     n,m = map(int,raw_input().split())
  5.     if n*(n+1)/2 < m :
  6.         print -1
  7.     else:
  8.         a,b,c = 1,1,-2*m
  9.         d = math.sqrt(1 - 4*a*c)
  10.         ans = int((-b+d)/2)
  11.         for i in range(max(ans-10,0),ans+10):
  12.             if i*(i+1)/2 >= m:
  13.                 ans = i
  14.                 break
  15.         print ans
Success #stdin #stdout 0s 23304KB
comments ()
stdin 
2
3 2
2 4
stdout 
2
-1
https://ideone.com/AJ9RHr
language:
Python (cpython 2.7.16)
created:
7 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!