栈和队列_leetcode127

class Solution(object):
    def ladderLength(self, beginWord, endWord, wordList):
        """
        :type beginWord: str
        :type endWord: str
        :type wordList: List[str]
        :rtype: int
        """


        pair = (beginWord,1)
        queue = []
        queue.append(pair)

        while queue:
            curPair = queue.pop(0)
            curWord = curPair[0]
            curStep = curPair[1]

            if curWord == endWord:
                return curStep

            nextWordList = self.getNextWordList(curWord,wordList)
            for nextWord in nextWordList:
                nextPair = (nextWord,curStep+1)
                queue.append(nextPair)

        return 0


    def getNextWordList(self,curWord,wordList):
        nextWordList = []

        for word in wordList:
            if self.isNextWord(curWord,word):
                nextWordList.append(word)

        return nextWordList

    def isNextWord(self,curWord,nextWord):
        diff = 0

        for i in range(len(curWord)):
            if curWord[i] != nextWord[i]:
                diff += 1
        return diff == 1

class Solution2(object):
    def ladderLength(self, beginWord, endWord, wordList):
        """
        :type beginWord: str
        :type endWord: str
        :type wordList: List[str]
        :rtype: int
        """

        visit = {}


        for word in wordList :
            visit[word] = False

        pair = (beginWord,1)
        queue = []
        queue.append(pair)



        while queue:
            curPair = queue.pop(0)
            curWord = curPair[0]
            curStep = curPair[1]

            if curWord == endWord:
                return curStep

            nextWordList = self.getNextWordList(curWord,wordList)

            for nextWord in nextWordList:
                if visit[nextWord] == False:
                    nextPair = (nextWord,curStep+1)
                    queue.append(nextPair)
                    visit[nextWord] = True


        return 0


    def getNextWordList(self,curWord,wordList):
        nextWordList = []

        for word in wordList:
            if self.isNextWord(curWord,word):
                nextWordList.append(word)

        return nextWordList

    def isNextWord(self,curWord,nextWord):
        diff = 0

        for i in range(len(curWord)):
            if curWord[i] != nextWord[i]:
                diff += 1

        return diff == 1

class Solution3(object):
    def ladderLength(self, beginWord, endWord, wordList):
        """
        :type beginWord: str
        :type endWord: str
        :type wordList: List[str]
        :rtype: int
        """

        visit = {}
        wordList = set(wordList)

        for word in wordList :
            visit[word] = False

        pair = (beginWord,1)
        queue = []
        queue.append(pair)



        while queue:
            curPair = queue.pop(0)
            curWord = curPair[0]
            curStep = curPair[1]

            if curWord == endWord:
                return curStep

            nextWordList = self.getNextWordList(curWord, wordList)
            for nextWord in nextWordList:
                if visit[nextWord] == False:
                    nextPair = (nextWord,curStep+1)
                    queue.append(nextPair)
                    visit[nextWord] = True
                    wordList.remove(nextWord)

        return 0


    def getNextWordList(self,curWord,wordList):
        nextWordList = []

        for word in wordList:
            if self.isNextWord(curWord,word):
                nextWordList.append(word)

        return nextWordList

    def isNextWord(self,curWord,nextWord):
        diff = 0

        for i in range(len(curWord)):
            if curWord[i] != nextWord[i]:
                diff += 1

        return diff == 1

# 这种数据过滤的优化思路真的吊class Solution4(object):    def ladderLength(self, beginWord, endWord, wordList):        """        :type beginWord: str        :type endWord: str        :type wordList: List[str]        :rtype: int        """        wordset = set(wordList)        bfs = collections.deque()        bfs.append((beginWord, 1))        while bfs:            word, length = bfs.popleft()            if word == endWord:                return length            for i in range(len(word)):                for c in "abcdefghijklmnopqrstuvwxyz":                    newWord = word[:i] + c + word[i + 1:]                    if newWord in wordset and newWord != word:                        wordset.remove(newWord)                        bfs.append((newWord, length + 1))        return 0class Solution5(object):    def ladderLength(self, beginWord, endWord, wordList):        """        :type beginWord: str        :type endWord: str        :type wordList: List[str]        :rtype: int        """        visit = {}        wordList = set(wordList)        for word in wordList :            visit[word] = False        pair = (beginWord,1)        queue = []        queue.append(pair)        while queue:            curPair = queue.pop(0)            curWord = curPair[0]            curStep = curPair[1]            if curWord == endWord:                return curStep            nextWordList = self.getNextWordList(curWord, wordList)            for nextWord in nextWordList:                if visit[nextWord] == False:                    nextPair = (nextWord,curStep+1)                    queue.append(nextPair)                    visit[nextWord] = True                    wordList.remove(nextWord)        return 0    def getNextWordList(self,curWord,wordList):        nextWordList = []        for word in wordList:            if self.isNextWord(curWord,word):                nextWordList.append(word)        return nextWordList    def isNextWord(self,curWord,nextWord):        diff = 0        for i in range(len(curWord)):            if curWord[i] != nextWord[i]:                diff += 1        return diff == 1b = "hit"e = "cog"wl = ["hot","dot","dog","lot","log","cog"]wl2 = ["hot","dot","dog","lot","log"]s = Solution2()print s.ladderLength(b,e,wl)