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"""
https://leetcode.com/problems/search-for-a-range/description/
"""

class Solution(object):
    def searchRange(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[int]
        >>> s = Solution()
        >>> s.searchRange([5, 7, 7, 8, 8, 10], 8)
        [3, 4]
        >>> s.searchRange([5, 7, 7, 8, 8, 10], 6)
        [-1, -1]
        >>> s.searchRange([], 0)
        [-1, -1]
        >>> s.searchRange([1], 1)
        [0, 0]
        >>> s.searchRange([1, 3], 1)
        [0, 0]
        >>> s.searchRange([1, 4], 4)
        [1, 1]
        >>> s.searchRange([2, 2], 2)
        [0, 1]
        """
        start = 0
        end = len(nums)
        if end == 0:
            return [-1, -1]
        ex = -1
        while True:
            if end - start == 1:
                if nums[start] == target:
                    ex = start
                break
            mid_ind = (start+end)//2
            mid = nums[mid_ind]
            if mid > target:
                end = mid_ind
            elif mid < target:
                start = mid_ind
            else:
                ex = mid_ind
                break
        # cannot find target in nums.
        if ex == -1:
            return [-1, -1]

        start = ex
        end = ex

        # extend to the end.
        for idx in range(ex+1, len(nums)):
            if nums[idx] == target:
                end = idx
            else:
                break
        # extend to the start.
        for idx in range(ex-1, -1, -1):
            if nums[idx] == target:
                start = idx
            else:
                break
        
        return [start, end]

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"""
https://leetcode.com/problems/string-to-integer-atoi/description/
"""


class Solution(object):
    def myAtoi(self, st):
        """
        :type str: str
        :rtype: int
        >>> s = Solution()
        >>> s.myAtoi("42")
        42
        >>> s.myAtoi("   -42")
        -42
        >>> s.myAtoi("4193 with words")
        4193
        >>> s.myAtoi("words and 987")
        0
        >>> s.myAtoi("-91283472332")
        -2147483648
        >>> s.myAtoi("  -12-45")
        -12
        >>> s.myAtoi("-")
        0
        >>> s.myAtoi("- 1")
        0
        >>> s.myAtoi("- 1")
        0
        >>> s.myAtoi("- -1")
        0
        >>> s.myAtoi("+1")
        1
        >>> s.myAtoi("123  456")
        123
        """
        INT_MAX = 2**31 - 1
        INT_MIN = -2**31
        start, end = -1, -1
        if st == "":
            return 0
        for idx, i in enumerate(st):
            if i == " ":
                if start != -1:
                    end = idx
                    break
            elif i in set({"-", "+"}):
                if start == -1:
                    start = idx
                else:
                    end = idx
                    break

            elif i in set({"0", "1", "2", "3", "4", "5", "6", "7", "8", "9"}):
                if start == -1:
                    start = idx
            else:
                if start == -1:
                    return 0
                else:
                    end = idx
                    break
        try:
            if end == -1:
                value = int(st[start:])
            else:
                value = int(st[start:end])
        except ValueError:
            return 0
        if value > INT_MAX:
            return INT_MAX
        if value < INT_MIN:
            return INT_MIN
        return value

    def myAtoi2(self, st):
        """
        :type str: str
        :rtype: int
        """
        import re
        st = st.strip()
        try:
            res = re.search('(^[\+\-]?\d+)', st).group()
            res = int(res)
            res = res if res <= 2147483647 else 2147483647
            res = res if res >= -2147483648 else -2147483648
        except:
            res = 0
        return res

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class Solution(object):
    def myPow(self, x, n):
        """
        :type x: float
        :type n: int
        :rtype: float
        >>> s = Solution()
        >>> s.myPow(2.00000, 10)
        1024.00000
        >>> s.myPow(2.10000, 3)
        9.26100
        """
        # change n to position, check whether x is 1 or -1
        if n == 0:
            return 1
        elif n > 0:
            pass
        else:
            n = -n
            x = 1 / x
        if x == 1:
            return 1
        if x == -1:
            return 1 if n % 2 == 0 else -1
        return self.pow(x, n)

    def pow(self, x, n):
        # n is positive
        if n == 0:
            return 1
        if n == 1:
            return x
        if n % 2 == 0:
            return self.pow(x, n/2)**2
        else:
            return x*self.pow(x, n/2)**2


if __name__ == '__main__':
    s = Solution()
    print(s.myPow(0.000001, 2111121))

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"""
https://leetcode.com/problems/reverse-integer/description/
"""

class Solution(object):
    def reverse(self, x):
        """
        :type x: int
        :rtype: int
        >>> s = Solution()
        >>> s.reverse(123)
        321
        >>> s.reverse(0)
        0
        >>> s.reverse(-123)
        -321
        >>> s.reverse(2**31)
        0
        >>> s.reverse(1563847412)
        0
        """
        if x == 0:
            return x
        if x < 0:
            sig = -1
        else:
            sig = 1
        s = int((str(abs(x))[::-1]))
        if sig < 0:
            if s > 2**31:
                return 0
        else:
            if s > 2**31 - 1:
                return 0
        if sig == -1:
            s = -s
        return s


def test():
    s = Solution()
    s.reverse(123)
    s.reverse(0)
    s.reverse(-123)
    s.reverse(2**31)
    s.reverse(1563847412)


if __name__ == '__main__':
	import timeit
	print(timeit.timeit("test()", number=100000, setup="from __main__ import test"))

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“””
https://leetcode-cn.com/problems/longest-substring-without-repeating-characters/description/
无重复字符的最长子串
“””

class Solution(object):
def lengthOfLongestSubstring(self, s):
“””
:type s: str
:rtype: int
>>> s = Solution()
>>> s.lengthOfLongestSubstring(“aab”)
2
>>> s.lengthOfLongestSubstring(“dvdf”)
3
>>> s.lengthOfLongestSubstring(“abcabcbb”)
3
>>> s.lengthOfLongestSubstring(“abcabcbb”)
3
>>> s.lengthOfLongestSubstring(“abba”)
2
>>> s.lengthOfLongestSubstring(“aaaaaaa”)
1
>>> s.lengthOfLongestSubstring(“a”)
1
>>> s.lengthOfLongestSubstring(“”)
0
“””
if s == “”:
return 0
if len(s) == 1:
return 1

# 记录字符到index的映射
dic = {}
L, start_ind = 0, 0
for idx, i in enumerate(s):
    # 第idx个字符在dic中且是超过start_ind的字符
    if i in dic and start_ind <= dic[i]:
        L = max(idx - start_ind, L)
        start_ind = dic[i] + 1
    dic[i] = idx
L = max(idx + 1 - start_ind, L)
return L

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"""
https://leetcode-cn.com/problems/add-two-numbers/description/

copy codes.
"""
class ListNode:
    def __init__(self, x):
        self.val = x
        self.next = None


class Solution(object):
    def addTwoNumbers(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        dummy = ListNode(0)
        current, carry = dummy, 0
        while l1 or l2:
            val = carry
            if l1:
                val += l1.val
                l1 = l1.next
            if l2:
                val += l2.val
                l2 = l2.next
            carry, val = divmod(val, 10)
            current.next = ListNode(val)
            current = current.next
        if carry == 1:
            current.next = ListNode(1)
        return dummy.next


if __name__ == '__main__':
    a, a.next, a.next.next = ListNode(2), ListNode(4), ListNode(3)
    b, b.next, b.next.next = ListNode(5), ListNode(6), ListNode(4)
    result = Solution().addTwoNumbers(a, b)
    print("{0} -> {1} -> {2}".format(result.val, result.next.val,
                                     result.next.next.val))

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"""
https://leetcode-cn.com/problems/two-sum/description/
"""
class Solution(object):
    def twoSum(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[int]
        >>> s = Solution()
        >>> nums = [3, 2, 4]
        >>> target = 6
        >>> s.twoSum(nums, target)
        [1, 2]
        """
        # tmp = [target - i for i in nums]
        # for idx, i in enumerate(tmp):
        #     try:
        #         idx2 = nums.index(i)
        #         if idx2 != idx:
        #             return [idx, idx2]
        #     except ValueError:
        #         pass

        dic = {}
        for idx, num in enumerate(nums):
            if target - num in dic:
                return [dic[target-num], idx]
            dic[num] = idx

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"""
MSP(max sub-array problem)
wiki(https://en.wikipedia.org/wiki/Maximum_subarray_problem).

1-D:
    kadene's algorithm time complexity: O(n)
2-D:
    ~=O(n^3)
"""
import numpy as np
from itertools import combinations, accumulate


def msp_1D(A):
    """
    1D array MSP.

    Parameters
    ----------
    A: list or np.ndarray

    Returns
    -------
    max_so_far: max sum of subarraies.
 
    >>> A = np.array([1, 2, 3, 0, -1, -2, 3, 4, 1, -2, 0])
    >>> max_so_far = msp_1D(A)
    >>> max_so_far == 11
    True
    """
    max_ending_here = max_so_far = 0
    for x in A:
        max_ending_here = max(0, max_ending_here + x)
        max_so_far = max(max_so_far, max_ending_here)
    return max_so_far


def msp_1D_with_index(A):
    """
    solve 1D max sub-array problem.
    
    Parameters
    ----------
    A: list or np.ndarray

    Returns
    -------
    start_ind: int
    end_ind: int
    max_so_far: max sum of subarraies.
    
    That is to say:
    >>> A = np.array([1, 2, 3, 0, -1, -2, 3, 4, 1, -2, 0])
    >>> start_ind, end_ind, max_so_far = msp_1D_with_index(A)
    >>> start_ind, end_ind, max_so_far
    (0, 8, 11)
    >>> sum(A[start_ind:end_ind+1]) == max_so_far
    True
    """
    start_ind, end_ind = 0, 0
    max_ending_here, max_so_far = 0, 0
    for idx, x in enumerate(A):
        max_ending_here1 = max_ending_here + x
        if max_ending_here1 > 0:
            max_ending_here = max_ending_here1
        else:
            # start with this idx.
            start_ind = idx + 1
            max_ending_here = 0
        if max_so_far < max_ending_here:
            # end with this idx.
            end_ind = idx
            max_so_far = max_ending_here
    return start_ind, end_ind, max_so_far


def msp_2D(A):
    """
    2D array MSP.
    
    Parameters
    ----------
    A: np.ndarray

    Returns
    -------
    start_ind: int
    end_ind: int
    max_so_far: max sum of subarraies.
    
    Steps
    -----
    1. caculate acc matrix(accumulate of A).
    2. for all indexes i, j pairs(i<j),
        calculating sum of block for a k column(using acc matrix).
        do 1-d MSP(get a max sum block under i, j)
    3. return the max.

    >>> A = np.array([\
        [0, -2, -7, 0],\
        [9, 2, -6, 2],\
        [-4, 1, -4, 1],\
        [-1, 8, 0, -2]])
    >>> m = msp_2D(A)
    >>> m == 15
    True
    """
    A = np.array(A)
    acc = np.array([*accumulate(A)])
    m = 0
    for i, j in combinations(range(A.shape[0]), 2):
        m_tmp = msp_1D([
            acc[j, k] - acc[i - 1, k] if i != 0 else acc[j, k]
            for k in range(A.shape[1])
        ])
        if m_tmp > m:
            m = m_tmp
    return m


def msp_2D_with_index(A):
    """
    2D array MSP.
    
    Parameters
    ----------
    A: np.ndarray

    Returns
    -------
    start_ind: tuple
        max sum block left-top position.
    end_ind: tuple
        max sum block right-bottom position.
    max_so_far: max sum of subarraies.
    
    That is to say:
    >>> A = np.array([\
        [0, -2, -7, 0],\
        [9, 2, -6, 2],\
        [-4, 1, -4, 1],\
        [-1, 8, 0, -2]])
    >>> start_ind, end_ind, m = msp_2D_with_index(A)
    >>> A[start_ind[0]:end_ind[0]+1, start_ind[1]:end_ind[1]+1].sum() == m
    True
    """
    A = np.array(A)
    acc = np.array([*accumulate(A)])
    start_ind, end_ind, m = None, None, 0
    for i, j in combinations(range(A.shape[0]), 2):
        sind, eind, m_tmp = msp_1D_with_index([
            acc[j, k] - acc[i - 1, k] if i != 0 else acc[j, k]
            for k in range(A.shape[1])
        ])
        if m_tmp > m:
            m = m_tmp
            start_ind = (i, sind)
            end_ind = (j, eind)
    return start_ind, end_ind, m

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sudo apt-get install xscreensaver xscreensaver-gl-extra xscreensaver-data-extra
  • Atlantis
  • boxed
  • FadePlot
  • FlipFlop
  • GLMatrix
  • Grav
  • Juggler3D
  • Pacman
  • Rubik

锁屏进入屏保

1
xscreensaver-command -lock

或者自带的屏保gnome-screensaver

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# python3
import collections
 
# 初始化字典
dict1 = { 'a' : 1, 'b' : 2 }
dict2 = { 'b' : 3, 'c' : 4 }
 
# 初始化ChainMap
chain = collections.ChainMap(dict1, dict2)
 
# 使用maps输出chainMap
print(chain.maps)  # [{'b': 2, 'a': 1}, {'b': 3, 'c': 4}]
 
# 输出key
print(list(chain.keys()))  # ['b', 'c', 'a']
 
# 输出值
print(list(chain.values())) # [2, 4, 1]
 
# 访问
print(chain['b'])  # 2
print(chain.get('b'))  # 2
 
# 使用new_child添加新字典
dict3 = { 'f' : 5 }
new_chain = chain.new_child(dict3)
print (new_chain.maps)  # [{'f': 5}, {'b': 2, 'a': 1}, {'b': 3, 'c': 4}]
 
new_chain.maps = reversed(new_chain.maps)
print(new_chain.maps)