lc_1~lc_10

1、采用hash表的形式解决该问题

题目中的示例：

i	dif	if_true	hash
0	dif=target-nums[0]=26-2=24	false	{2:0}
1	dif=26-7=19	false	{2:0,7:1}
2	dif=26-7=19	false	{2:0,7:2}
3	dif=26-11=15	false	{2:0,7:2,11:3}
4	dif=26-15=11	true
5

class Solution:
    def twoSum(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[int]
        """
        
        nums_hash = {}
        nums_len = len(nums)
        
        for i in range(nums_len):
            dif = target - nums[i]
            if dif in nums_hash:
                return [nums_hash[dif], i]
            nums_hash[nums[i]] = i
            print(dif, nums_hash)
            
        return []

if __name__ == '__main__':
    nums = [2,7,7,11,15]
    target = 26
    a = Solution()
    r = a.twoSum(nums, target)
    print(r)

2、链表（ListNode）的处理方式

题目中的示例：

步骤	l1.val	l2.val	carry	pre.val	res.val
0			0	0	0
2	2	5	0	7	7
3	4	6	0	0	0
4	3	4	1	8	8

class ListNode:
    def __init__(self, x):
        self.val = x
        self.next = None
        
class Solution:
    def addTwoNumbers(self, l1, l2):
        '''
        :type l1: ListNode
        :type l2: ListNode
        :type l3: ListNode
        '''
        carry = 0
        res = pre = ListNode(0)
        while(l1 or l2 or carry):
            if l1:
                carry += l1.val

                l1 = l1.next
            if l2:
                carry += l2.val
                l2 = l2.next
            carry, val = divmod(carry, 10)
            pre.next = pre = ListNode(val)
        return res.next

if __name__ == '__main__':
    
    sol = Solution()
    l1 = ListNode(2)
    l1.next = l11 = ListNode(4)
    l11.next = l12 = ListNode(3)
    
    
    l2 = ListNode(5)
    l2.next = l21 = ListNode(6)
    l21.next = l22 = ListNode(4)

    res = sol.addTwoNumbers(l1, l2)
    while res:
        print(res.val)
        res = res.next

class Solution:
    def lengthOfLongestSubstring(self, s):
        '''
        :type s: str
        :rtype: int
        '''
        dic = {}
        star = 0
        temp = 0
        max_len = 0
        for i in range(len(s)):
            if s[i] in dic:
                star = max(star, dic[s[i]] + 1)
            dic[s[i]] = i
            temp = i + 1 - star
            max_len = max(temp, max_len)
        return max_len


if __name__ == '__main__':
    sol = Solution()
    print(sol.lengthOfLongestSubstring('abcabcdabgf'))
    print(sol.lengthOfLongestSubstring('pwwkew'))
    print(sol.lengthOfLongestSubstring('bbbbb'))
    print(sol.lengthOfLongestSubstring('ababaab'))
    print(sol.lengthOfLongestSubstring(''))

8.

class Solution:
    def myAtoi(self, str):
        dic = {}
        flag = 1
        nums = 0
        dic.update({'1':1,'2':2,'3':3,'4':4,'5':5,'6':6,'7':7,'8':8,'9':9,'0':0})
        k = 0
        while k < len(str):
            
            if str[k] == ' ':
                if nums==0 and flag == 1:
                    k = k + 1
                else:
                    break
                
            if str[k] == '-':
                if nums==0:
                    k = k + 1
                    flag = -1
                else:
                    break
                
            
            if str[k] in dic:
                nums = nums*10 + dic[str[k]]
                print(k, str[k])
                k = k + 1
                continue
                
            if (str[k] not in dic) and (str[k] != ' ') and (str[k] != '-'):
                break
        return flag * nums
    
if __name__ == '__main__':
    sol = Solution()
    print(sol.myAtoi('+'))