LeetCode 705. Design HashSet

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题目

Design a HashSet without using any built-in hash table libraries.

To be specific, your design should include these functions:

  • add(value): Insert a value into the HashSet.
  • contains(value) : Return whether the value exists in the HashSet or not.
  • remove(value): Remove a value in the HashSet. If the value does not exist in the HashSet, do nothing.

Example:

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MyHashSet hashSet = new MyHashSet();
hashSet.add(1);         
hashSet.add(2);         
hashSet.contains(1);    // returns true
hashSet.contains(3);    // returns false (not found)
hashSet.add(2);          
hashSet.contains(2);    // returns true
hashSet.remove(2);          
hashSet.contains(2);    // returns false (already removed)

Note:

  • All values will be in the range of [0, 1000000].
  • The number of operations will be in the range of [1, 10000].
  • Please do not use the built-in HashSet library.

思路

Note: All values will be in the range of [0, 1000000].
所以直接开辟这么大的一个数组，然后全部设置成False，哪里有数字哪里就是True.

代码

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class MyHashSet(object):

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.hash_set = [False]*1000001

    def add(self, key):
        """
        :type key: int
        :rtype: None
        """
        self.hash_set[key] = True

    def remove(self, key):
        """
        :type key: int
        :rtype: None
        """
        self.hash_set[key] = False

    def contains(self, key):
        """
        Returns true if this set contains the specified element
        :type key: int
        :rtype: bool
        """
        return self.hash_set[key]


# Your MyHashSet object will be instantiated and called as such:
# obj = MyHashSet()
# obj.add(key)
# obj.remove(key)
# param_3 = obj.contains(key)