valid-anagram.py

# Time:  O(n)
# Space: O(1)
#
# Given two strings s and t, write a function to
# determine if t is an anagram of s.
#
# For example,
# s = "anagram", t = "nagaram", return true.
# s = "rat", t = "car", return false.
#
# Note:
# You may assume the string contains only lowercase alphabets.
#

class Solution:
    # @param {string} s
    # @param {string} t
    # @return {boolean}
    def isAnagram(self, s, t):
        if len(s) != len(t):
            return False

        count = {}

        for c in s:
            if c.lower() in count:
                count[c.lower()] += 1
            else:
                count[c.lower()] = 1

        for c in t:
            if c.lower() in count:
                count[c.lower()] -= 1
            else:
                count[c.lower()] = -1
            if count[c.lower()] < 0:
                return False

        return True
    
    def isAnagram2(self, s, t):
        return all([s.count(c)==t.count(c) for c in string.ascii_lowercase])
    
    def isAnagram3(self, s, t):
        if len(s) != len(t):
            return False 
        count = collections.defaultdict(int)
        for c in s:
            count[c] += 1
        for c in t:
            count[c] -= 1
            if count[c] < 0:
                return False
        return True

# Time:  O(nlogn)
# Space: O(n)
class Solution2:
    # @param {string} s
    # @param {string} t
    # @return {boolean}
    def isAnagram(self, s, t):
        return sorted(s) == sorted(t)