HackerRank Lily's Homework

https://www.hackerrank.com/challenges/lilys-homework/problem

提出

code: python

#!/bin/python3

import math

import os

import random

import re

import sys

# Complete the 'lilysHomework' function below.

# The function is expected to return an INTEGER.

# The function accepts INTEGER_ARRAY arr as parameter.

def lilysHomework(arr):

# Write your code here

# change = True

# ans = 0

# for i in range(len(arr)):

# if not change:

# break

# change = False

# for j in range(len(arr) - i - 1):

# if arrj > arrj + 1:

# arrj, arrj + 1 = arrj + 1, arrj

# ans += 1

# change = True

# return ans // 2

if __name__ == '__main__':

fptr = open(os.environ'OUTPUT_PATH', 'w')

n = int(input().strip())

arr = list(map(int, input().rstrip().split()))

result = lilysHomework(arr)

fptr.write(str(result) + '\n')

fptr.close()

解答

code: python

#!/bin/python3

import math

import os

import random

import re

import sys

# Complete the 'lilysHomework' function below.

# The function is expected to return an INTEGER.

# The function accepts INTEGER_ARRAY arr as parameter.

def lilysHomework(arr):

# Write your code here

# create function to find no. of swaps

def no_of_swaps(arr):

indexmap = {}

for i in range(len(arr)):

indexmap[arri] = i

# print(indexmap)

# {2: 0, 5: 1, 3: 2, 1: 3}

# arr -> 2, 5, 3, 1

# sorted_arr -> 1, 2, 3, 5

sorted_arr = sorted(arr)

result = 0

for i in range(len(arr)):

if arri != sorted_arri:

result += 1

# swap element index

swap_index = indexmap[sorted_arri]

# swap operation

arri, arrswap_index = arrswap_index, arri

# update swapping index

indexmap[arri] = swap_index

indexmap[sorted_arri] = i

return result

# Loop 1 (i=0):

# - arr0=2 != sorted_arr0=1, need swap

# - swap_index = indexmap1 = 3

# - Swap arr0 and arr3

# - Update indexmap2 = 3

# - Update indexmap1 = 0

# indexmap = {1: 0, 5: 1, 3: 2, 2: 3}

# - New state: arr = 1, 5, 3, 2

# Loop 2 (i=1):

# - arr1=5 != sorted_arr1=2, need swap

# - swap_index = indexmap2 = 3

# - Swap arr1 and arr3

# - Update indexmap5 = 3

# - Update indexmap2 = 2

# indexmap = {1: 0, 2: 1, 3: 2, 5: 3}

# - New state: arr = 1, 2, 3, 5

# Loop 3 (i=2):

# - arr2=3 == sorted_arr2=3, no swap needed

# - State remains unchanged

# Loop 4 (i=3):

# - arr3=5 == sorted_arr3=5, no swap needed

# - State remains unchanged

normal_order = no_of_swaps(arr::)

reverse_order = no_of_swaps(arr::-1)

return min(normal_order, reverse_order)

if __name__ == '__main__':

fptr = open(os.environ'OUTPUT_PATH', 'w')

n = int(input().strip())

arr = list(map(int, input().rstrip().split()))

result = lilysHomework(arr)

fptr.write(str(result) + '\n')

fptr.close()

提出

code: python

#!/bin/python3

import math

import os

import random

import re

import sys

# Complete the 'lilysHomework' function below.

# The function is expected to return an INTEGER.

# The function accepts INTEGER_ARRAY arr as parameter.

# 3 4 2 5 1

# 5 4 2 3 1

# 5 4 3 2 1

def lilysHomework(arr):

# Write your code here

ans = bubble_sort(arr)

return ans

if __name__ == '__main__':

fptr = open(os.environ'OUTPUT_PATH', 'w')

n = int(input().strip())

arr = list(map(int, input().rstrip().split()))

result = lilysHomework(arr)

fptr.write(str(result) + '\n')

fptr.close()

code: python

#!/bin/python3

import math

import os

import random

import re

import sys

import copy

# Complete the 'lilysHomework' function below.

# The function is expected to return an INTEGER.

# The function accepts INTEGER_ARRAY arr as parameter.

# 2, 5, 3, 1

# 1, 2, 3, 5

def lilysHomework(arr):

sorted_arr = sorted(arr.copy())

# how to swap

if __name__ == '__main__':

fptr = open(os.environ'OUTPUT_PATH', 'w')

n = int(input().strip())

arr = list(map(int, input().rstrip().split()))

result = lilysHomework(arr)

fptr.write(str(result) + '\n')

fptr.close()