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Diffstat (limited to 'challenge-243/jeanluc2020/python/ch-1.py')
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diff --git a/challenge-243/jeanluc2020/python/ch-1.py b/challenge-243/jeanluc2020/python/ch-1.py new file mode 100755 index 0000000000..c557de5347 --- /dev/null +++ b/challenge-243/jeanluc2020/python/ch-1.py @@ -0,0 +1,53 @@ +#!/usr/bin/python3 +# https://theweeklychallenge.org/blog/perl-weekly-challenge-243/#TASK1 +# +# Task 1: Reverse Pairs +# ===================== +# +# You are given an array of integers. +# +# Write a script to return the number of reverse pairs in the given +# array. +# +# A reverse pair is a pair (i, j) where: a) 0 <= i < j < nums.length +# and b) nums[i] > 2 * nums[j]. +# +## Example 1 +## +## Input: @nums = (1, 3, 2, 3, 1) +## Output: 2 +## +## (1, 4) => nums[1] = 3, nums[4] = 1, 3 > 2 * 1 +## (3, 4) => nums[3] = 3, nums[4] = 1, 3 > 2 * 1 +# +## Example 2 +## +## Input: @nums = (2, 4, 3, 5, 1) +## Output: 3 +## +## (1, 4) => nums[1] = 4, nums[4] = 1, 4 > 2 * 1 +## (2, 4) => nums[2] = 3, nums[4] = 1, 3 > 2 * 1 +## (3, 4) => nums[3] = 5, nums[4] = 1, 5 > 2 * 1 +# +############################################################ +## +## discussion +## +############################################################ +# +# Walk the array twice (once from 0, once from the first index + 1) +# Check the condition in each case, counting the occurrences where +# the condition holds true. + +def reverse_pairs(nums: list): + print("Input: (", ", ".join(str(x) for x in nums), ")") + result = 0 + for i in range(len(nums)): + for j in range(i+1, len(nums)): + if nums[i] > 2 * nums[j]: + result += 1 + print("Output:", str(result)) + +reverse_pairs( [ 1, 3, 2, 3, 1 ] ); +reverse_pairs( [ 2, 4, 3, 5, 1 ] ); + |