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shuffle-an-array.py
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shuffle-an-array.py
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'''
Shuffle a set of numbers without duplicates.
Example:
// Init an array with set 1, 2, and 3.
int[] nums = {1,2,3};
Solution solution = new Solution(nums);
// Shuffle the array [1,2,3] and return its result. Any permutation of [1,2,3] must equally likely to be returned.
solution.shuffle();
// Resets the array back to its original configuration [1,2,3].
solution.reset();
// Returns the random shuffling of array [1,2,3].
solution.shuffle();
'''
# 注意python中,引用和副本的区别
# Approach one
# import random
# class Solution:
# def __init__(self, nums):
# """
# :type nums: List[int]
# """
# self.nums = nums[:] # 没有[:]是,使用的是numsp[:]的引用; 而加上后,使用的是[:]的副本,副本不会改变
# self.output = nums
# def reset(self):
# """
# Resets the array to its original configuration and return it.
# :rtype: List[int]
# """
# return self.nums
# def shuffle(self):
# """
# Returns a random shuffling of the array.
# :rtype: List[int]
# """
# length = len(self.output)
# for i in range(length):
# j = random.randint(0,length-1)
# self.output[i], self.output[j] = self.output[j], self.output[i]
# return self.output
# Approach two
import random
class Solution:
def __init__(self, nums):
"""
:type nums: List[int]
"""
self.nums = nums
def reset(self):
"""
Resets the array to its original configuration and return it.
:rtype: List[int]
"""
return self.nums
def shuffle(self):
"""
Returns a random shuffling of the array.
:rtype: List[int]
"""
self.output = self.nums.copy() # 需要打乱顺序的时候,拷贝新的副本,不改变原本的数据
length = len(self.output)
for i in range(length):
j = random.randint(0,length-1)
self.output[i], self.output[j] = self.output[j], self.output[i]
return self.output
# Your Solution object will be instantiated and called as such:
# obj = Solution(nums)
# param_1 = obj.reset()
# param_2 = obj.shuffle()