We use cookies to ensure you have the best browsing experience on our website. Please read our cookie policy for more information about how we use cookies.
  1. All Contests
  2. ProjectEuler+
  3. Project Euler #42: Coded triangle numbers
  4. Discussions

Project Euler #42: Coded triangle numbers

Sort by

recency

|

25 Discussions

|

  • hamblinglen
     + 0 comments

    python

    from math import sqrt
for _ in range(int(input())):
    n = int(input())
    s = sqrt(1+8*n)
    if s % 2 == 1:
        print(int((s - 1) // 2))
    else:
        print(-1)

  • Rayaan2009
     + 0 comments

    Umm... Solution for Python 3 I think So!!!

    import math

a, b, c = 1, 1, -2

def solve_quadratic(N):
    D = int(math.sqrt(b**2 - 4 * a * c * N))
    n1 = (-b - D) // (2 * a)
    n2 = (-b + D) // (2 * a)
    
    if n1 > 0 and N == n1 * (n1 + 1) // 2:
        return n1
    elif n2 > 0 and N == n2 * (n2 + 1) // 2:
        return n2
    else:
        return -1

def main():
    num_cases = int(input().strip())
    for _ in range(num_cases):
        N = int(input().strip())
        result = solve_quadratic(N)
        print(result)

if __name__ == "__main__":
    main()

  • srikv
     + 0 comments

    100% python - uses qudratic formula

    import math

a, b, c = 1, 1, -2

for a0 in range(int(input())):
    N = int(input())
    D = int(math.sqrt((b**2 - 4 * a * c * N)))
    n1, n2 = (-b-D)//(2*a), (-b+D)//(2*a)
    #print(N, n1, n2)
    if n1 > 0 and N == n1*(n1+1)//2:
        print(n1)
    elif n2> 0 and N == n2*(n2+1)//2:
        print(n2)
    else:
        print(-1)

  • Someshraj09
     + 0 comments

    Easy solution in Python-3 ''' T = int(input().strip()) for _ in range(T): T_th_n = int(input().strip()) N = ((1 + 8*T_th_n)**0.5-1)/2 if N == int(N): print(int(N)) else: print(-1) '''

    Approach:-

    The code uses a for loop to iterate over a range of T test cases. For each test case, it takes an input T_th_n and calculates N using a mathematical formula. If N is an integer, it prints the integer value of N. Otherwise, it prints -1. The approach seems to be solving a mathematical problem related to finding the value of N.

  • Venkateshgurram5
     + 0 comments

    Easy solution in Python 3

    t=int(input().strip())
for _ in range(t):
    tn=int(input().strip())
    a=((1+8*tn)**0.5-1)/2
    if a==int(a):
        print(int(a))
    else:
        print(-1)