Lesson6-Triangle.py

# An array A consisting of N integers is given. 
# A triplet (P, Q, R) is triangular if 0 ≤ P < Q < R < N and:
# 
# A[P] + A[Q] > A[R],
# A[Q] + A[R] > A[P],
# A[R] + A[P] > A[Q].
# For example, consider array A such that:
# 
#   A[0] = 10    A[1] = 2    A[2] = 5
#   A[3] = 1     A[4] = 8    A[5] = 20
# Triplet (0, 2, 4) is triangular.
# 
# Write a function:
# 
# def solution(A)
# 
# that, given an array A consisting of N integers, 
# returns 1 if there exists a triangular triplet for this array and returns 0 otherwise.
# 
# For example, given array A such that:
# 
#   A[0] = 10    A[1] = 2    A[2] = 5
#   A[3] = 1     A[4] = 8    A[5] = 20
# the function should return 1, as explained above. Given array A such that:
# 
#   A[0] = 10    A[1] = 50    A[2] = 5
#   A[3] = 1
# the function should return 0.
# 
# Write an efficient algorithm for the following assumptions:
# 
# N is an integer within the range [0..100,000];
# each element of array A is an integer within the range [−2,147,483,648..2,147,483,647].

def solution(A):
    A.sort()

    for i in range(1, len(A)-1):
        if A[i] + A[i-1] > A[i+1]:
            return 1

    return 0