Commit d5db77b

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	`1`	`+#!usr/bin/env python3`
	`2`	`+# -- coding:utf-8 --`
	`3`	`+'''`
	`4`	`+Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.`
	`5`	`+'''`
	`6`	`+`
	`7`	`+`
	`8`	`+class Solution(object):`
	`9`	`+ def generateParenthesis(self, n):`
	`10`	`+ """`
	`11`	`+ :type n: int`
	`12`	`+ :rtype: List[str]`
	`13`	`+ """`
	`14`	`+ result = []`
	`15`	`+ self.generate(n, n, "", result)`
	`16`	`+ return result`
	`17`	`+`
	`18`	`+ def generate(self, left, right, string, result):`
	`19`	`+ if left == 0 and right == 0:`
	`20`	`+ result.append(string)`
	`21`	`+ return`
	`22`	`+ if left > 0:`
	`23`	`+ self.generate(left - 1, right, string + "(", result)`
	`24`	`+ if right > left:`
	`25`	`+ self.generate(left, right - 1, string + ")", result)`
	`26`	`+`
	`27`	`+`
	`28`	`+if __name__ == "__main__":`
	`29`	`+ assert (Solution().generateParenthesis(3)) == ['((()))', '(()())', '(())()', '()(())', '()()()']`
	`30`	`+`

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	`1`	`+#!usr/bin/env python3`
	`2`	`+# -- coding:utf-8 --`
	`3`	`+'''`
	`4`	`+Given a linked list, swap every two adjacent nodes and return its head.`
	`5`	`+`
	`6`	`+For example,`
	`7`	`+Given 1->2->3->4, you should return the list as 2->1->4->3.`
	`8`	`+`
	`9`	`+Your algorithm should use only constant space. You may not modify the values in the list, only nodes itself can be changed.`
	`10`	`+`
	`11`	`+Subscribe to see which companies asked this question`
	`12`	`+'''`
	`13`	`+`
	`14`	`+`
	`15`	`+# Definition for singly-linked list.`
	`16`	`+class ListNode(object):`
	`17`	`+ def __init__(self, x):`
	`18`	`+ self.val = x`
	`19`	`+ self.next = None`
	`20`	`+`
	`21`	`+`
	`22`	`+class Solution(object):`
	`23`	`+ def swapPairs(self, head):`
	`24`	`+ """`
	`25`	`+ :type head: ListNode`
	`26`	`+ :rtype: ListNode`
	`27`	`+ """`
	`28`	`+ prev = ListNode(-1)`
	`29`	`+ prev.next = head`
	`30`	`+ temp = prev`
	`31`	`+ while temp.next and temp.next.next:`
	`32`	`+ node1 = temp.next`
	`33`	`+ node2 = temp.next.next`
	`34`	`+ temp.next = node2`
	`35`	`+ node1.next = node2.next`
	`36`	`+ node2.next = node1`
	`37`	`+ temp = temp.next.next`
	`38`	`+ return prev.next`

Lines changed: 42 additions & 0 deletions

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	`1`	`+#!usr/bin/env python3`
	`2`	`+# -- coding:utf-8 --`
	`3`	`+'''`
	`4`	`+Divide two integers without using multiplication, division and mod operator.`
	`5`	`+`
	`6`	`+If it is overflow, return MAX_INT.`
	`7`	`+'''`
	`8`	`+`
	`9`	`+`
	`10`	`+class Solution(object):`
	`11`	`+ def divide(self, dividend, divisor):`
	`12`	`+ """`
	`13`	`+ :type dividend: int`
	`14`	`+ :type divisor: int`
	`15`	`+ :rtype: int`
	`16`	`+ """`
	`17`	`+ MAX_INT = 2 ** 31 - 1`
	`18`	`+ sign = 1`
	`19`	`+ if dividend >= 0 and divisor < 0 or dividend <= 0 and divisor > 0:`
	`20`	`+ sign = -1`
	`21`	`+ dividend = abs(dividend)`
	`22`	`+ divisor = abs(divisor)`
	`23`	`+`
	`24`	`+ result = 0`
	`25`	`+ current = divisor`
	`26`	`+ currentR = 1`
	`27`	`+ while current <= dividend:`
	`28`	`+ current <<= 1`
	`29`	`+ currentR <<= 1`
	`30`	`+ while divisor <= dividend:`
	`31`	`+ current >>= 1`
	`32`	`+ currentR >>= 1`
	`33`	`+ if current <= dividend:`
	`34`	`+ dividend -= current`
	`35`	`+ result += currentR`
	`36`	`+ return min(sign * result, MAX_INT)`
	`37`	`+`
	`38`	`+`
	`39`	`+if __name__ == "__main__":`
	`40`	`+ assert Solution().divide(5, -1) == -5`
	`41`	`+ # assert Solution().divide(10, 2) == 5`
	`42`	`+`

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