下面和大家分享本人在leetcode上已經ace的題目原始碼（python3）： 本人會持續更新！～
class leetcode_solution(object):
def twosum_1(self,nums, target):
""":type nums: list[int]
:type target: int
:rtype: list[int]
"""'''
# 此解法複雜度為o(n^2)
new_nums =
for i in range(len(nums)):
for j in range(i+1,len(nums)):
if nums[i] + nums[j] == target:
return new_nums
'''# 此解法複雜度為o(n)
# 拓展：若解不唯一，可先將nums排序後進行下面操作，將全部符合對輸出
if len(nums)<= 1:
return false
else:
dict = {}
for i in range(len(nums)):
# 字典底層是用hash表實現的，無論字典中有多少元素，查詢的平雲複雜度均為o(1)
if num[i] in dict:
return [dict[nums[i]], i]
else:
dict[target - nums[i]] = i
def reverse_7(self,x):
""":type x: int
:rtype: int
"""max = 2**31 - 1
min = -1*2**31
if x < 0:
y = -1*int(str(-x)[::-1])
else:
y = int(str(x)[::-1])
if y > max or y < min:
return 0
return y
def ispalindrome_9(self, x):
renum = 0
if x < 0 or (x % 10 == 0 and x != 0):
return false
while x > renum:
renum = renum * 10 + x % 10
x /= 10
return x == renum or x == renum/10
def romantoint_13(self, s):
""":type s: str
:rtype: int
"""dic =
sum = 0
for i in range(len(s)-1):
if dic[s[i]] < dic[s[i+1]]:
sum -= dic[s[i]]
else:
sum += dic[s[i]]
return sum + dic[s[-1]]
def longestcommonprefix_14(self, strs):
""":type strs: list[str]
:rtype: str
"""if len(strs) == 0: # horizontal scanning/////another way: vertical scanning
return ''
prefix = strs[0]
for i in range(1,len(strs)):
while strs[i].find(prefix) != 0:
prefix = prefix[0:len(prefix)-1]
if prefix == '':
return ''
return prefix
def isvalid_20(self, s):
""":type s: str
:rtype: bool
"""'''
list =
a = b = c = 0
if len(s) == 0:
return true
for i in range(len(s)):
if s[i] == '(':
a += 1
if s[i] == '':
if len(list) != 0 and list[-1] == '','[':']'}
stack =
for i in s:
if i in dic.values():
elif i in dic.keys():
if stack == or dic[i] != stack.pop():
return false
else:
return false
return stack ==
def mergetwolists_21(self, l1, l2):
""":type l1: listnode
:type l2: listnode
:rtype: listnode
"""# definition for singly-linked list.
# class listnode:
# def __init__(self, x):
# self.val = x
# self.next = none
head = rear = listnode(0)
while l1 and l2:
if l1.val < l2.val:
rear.next = l1
l1 = l1.next
else:
rear.next = l2
l2 = l2.next
rear = rear.next
rear.next = l1 or l2
return head.next
def removeduplicates_26(self, nums):
""":type nums: list[int]
:rtype: int
"""if len(nums) == 0:
return 0
newtail = 0
for i in range(1,len(nums)):
if nums[i] != nums[newtail]:
newtail += 1
nums[newtail] = nums[i]
return newtail + 1
def removeelement_27(self, nums, val):
""":type nums: list[int]
:type val: int
:rtype: int
"""i = len(nums)
j = 0
if i == 0:
return 0
while j < i:
if nums[j] == val:
nums.pop(j)
i -= 1
else:
j += 1
return len(nums)
def strstr_28(self, haystack, needle):
""":type haystack: str
:type needle: str
:rtype: int
"""for i in range(len(haystack) - len(needle) +1):
if haystack[i:i+len(needle)] == needle:
return i
return -1
def searchinsert_35(self, nums, target):
""":type nums: list[int]
:type target: int
:rtype: int
"""return len([x for x in nums if x < target])
def countandsay(self, n):
""":type n: int
:rtype: str
"""
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