diff options
| -rw-r--r-- | 1.py | 3 | ||||
| -rw-r--r-- | 2.1.py | 58 |
2 files changed, 61 insertions, 0 deletions
@@ -0,0 +1,3 @@ +# given: two lists containing the same integers +# but one list contains an extra one +# find it and return it @@ -0,0 +1,58 @@ +#!/usr/bin/pytnon2 + +## You are given a list of "pegs" with their location (positive integers, asc order). +## these pegs can accept gears with radius > 1 +## the goal is the last gear to be spinning twice as fast as the 1st one for any given list +## if it's possible return the first gear's radius in a list [a,b] where the ratio is a/b +## if not return [-1,-1] + +from fractions import gcd +from functools import reduce + +# test +from random import seed +from random import random + +def simplify(ratio_nums): + return list(map(reduce(gcd, ratio_nums).__rfloordiv__, ratio_nums)) + +def solution(pegs): + if len(pegs) == 2: + r1_by_three = 2 * (pegs[1] - pegs[0]) + nums = [r1_by_three, 3] + return simplify(nums) + S = pegs[-1] - pegs[0] + if len(pegs) % 2 == 0: + C = 0 + for i in range (1, len(pegs) - 1): + C += (-1)**i * pegs[i] + r1_by_three = 2 * S - 4 * C + + r = [r1_by_three/3] + for i in range(len(pegs) -1): + r.append(pegs[i+1]-pegs[i]-r[i]) + if r[-1] < 1: + return [-1, -1] + if (r[0]) < 1 or (r[0]) > pegs[1]-pegs[0]-1: + return [-1, -1] + return simplify([r1_by_three, 3]) + else: + K = 0 + for i in range (1, len(pegs) - 2): + K += (-1)**i * pegs[i] + r1 = 2*S - 4*K - 4*pegs[-1] + 4*pegs[-2] + if r1 < 1: + return [-1, -1] + return [r1, 1] + +seed(1) + +def ran(): + return int(random() * 1000) + +for i in range(1,1000): + a=[ran(),ran(),ran(),ran(),ran(),ran()] + a.sort() + print(a) + print(solution(a)) + print("") |