开学周 真的好忙呀啊啊

32：

最长有效括号 想着要用动态规划却不会用。。。

抄别人方法 

class Solution(object):
    def longestValidParentheses(self, s):
        """
        :type s: str
        :rtype: int
        """
        n = len(s)
        stack = []
        mark = [0]*n
        for i in range(n):
            if s[i] == '(':
                stack.append(i)
            else:
                if stack == []:
                    mark[i] = 1
                else:
                    stack.pop()
        while stack != []:
            mark[stack.pop()] = 1

        leng = 0
        maxlen = 0
        for i in mark:
            if i == 0:
                leng += 1
            else:
                if leng>maxlen:
                    maxlen = leng
                leng = 0
        if leng>maxlen:
            maxlen = leng
        return maxlen
        
                

作者：yizhu-jia
链接：https://leetcode-cn.com/problems/longest-valid-parentheses/solution/chao-bie-ren-de-he-ge-da-0-bu-he-ge-da-1-1jlk/
来源：力扣（LeetCode）
著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。

 

接下来是几个二分查找  麻烦之处都在边界

33：

 

class Solution(object):
    def search(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: int
        """
        l = 0
        r = len(nums)-1
        while (l<=r):
            mid =( l + r) //2
            if nums[mid] == target:
                return mid
            if nums[mid]>= nums[l]:
                if target >= nums[l] and target <= nums[mid]:
                    r = mid -1
                else:
                    l = mid +1
            else:
                if target >= nums[mid] and target <= nums[r]:
                    l = mid +1
                else:
                    r = mid -1
        return -1

作者：yizhu-jia
链接：https://leetcode-cn.com/problems/search-in-rotated-sorted-array/solution/bian-jie-tiao-jian-nan-gao-qing-by-yizhu-3kze/
来源：力扣（LeetCode）
著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。

34：超级容易越界 不行就try吧

class Solution(object):
    def searchRange(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[int]
        """


        l = 0
        r = len(nums)-1
        rel = [-1,-1]
        while(l <= r):
            mid = (l+r)//2
            if nums[mid] == target:
                rel[0] = mid
                rel[1] = mid
                if rel[0] > 0:
                    while nums[rel[0]-1] == target  :
                        rel[0] -= 1
                        if  rel[0] == 0:
                            break
                if rel[1]+1 < len(nums) :
                    while nums[rel[1]+1] == target :
                        rel[1] += 1
                        if rel[1]+1 == len(nums) :
                            break
                return rel
            if nums[mid] < target:
                l = mid +1
            else:
                r = mid -1

        return rel

作者：yizhu-jia
链接：https://leetcode-cn.com/problems/find-first-and-last-position-of-element-in-sorted-array/solution/ru-he-jie-jue-yue-jie-wen-ti-cheng-liao-agekc/
来源：力扣（LeetCode）
著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。

 

35：

搜索插入位置

二分法击败9成人

 

    def searchInsert(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: int
        """
        l = 0
        r = len(nums)-1
        while(l <= r):
            mid = (l+r)//2
            if nums[mid] == target:
                return mid
            if target > nums[mid] :
                l = mid +1
            else:
                r = mid -1
        return l

 

 

36：有效的数独

 

直接暴力解

class Solution(object):
    def isValidSudoku(self, board):
        """
        :type board: List[List[str]]
        :rtype: bool
        """
        dictnum = {str(i):0 for i in range(10)}
        #先判断行
        for row in board:
            for each in row:
                if each != '.':
                    dictnum[each] += 1
                    if dictnum[each] == 2:
                        return False
            for num in dictnum:
                dictnum[num] = 0
        # 判断列
        for i in range(9):
            for row in board:
                if row[i] != '.':
                    dictnum[row[i]] += 1
                    if dictnum[row[i]] == 2:
                        return False
            for num in dictnum:
                dictnum[num] = 0
        # 判断九格
        for row in range(0,9,3):
            for col in range(0,9,3):
                for rows in board[row:row+3]:
                    for each in rows[col:col+3]:
                        if each != '.':
                            dictnum[each] += 1
                            if dictnum[each] == 2:
                                return False
                for num in dictnum:
                    dictnum[num] = 0
        return True


作者：yizhu-jia
链接：https://leetcode-cn.com/problems/valid-sudoku/solution/bao-li-jie-fa-ye-neng-chao-guo-9cheng-de-wki1/
来源：力扣（LeetCode）
著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。