leetcode -- Longest Consecutive Sequence -- 重点

class Solution(object):
def longestConsecutive(self, num):
"""
:type nums: List[int]
:rtype: int
"""
dict = {x:False for x in num} # False means not visited
maxLen = -1
for i in dict:
if dict[i] == False:
curr = i + 1; len1 = 0
while curr in dict and dict[curr] == False:
len1 += 1; dict[curr] = True; curr += 1
curr = i - 1; len2 = 0
while curr in dict and dict[curr] == False:
len2 += 1; dict[curr] = True; curr -= 1
maxLen = max(maxLen, 1 + len1 + len2)
return maxLen

自己重做

class Solution(object):
def longestConsecutive(self, nums):
"""
:type nums: List[int]
:rtype: int
"""
if len(nums) == 0: return 0
flag = {}
count = {}
for x in nums:
if x not in flag: flag[x] = False
if x in count:
count[x] += 1
else:
count[x] = 1

res = 0
for x in nums:

if not flag[x]:

flag[x] = True
cur = x; sub_count = 0;
for i in xrange(1, len(nums)):
cur = x + i
if cur in count:
flag[cur] = True
sub_count += 1
else:
break
cur = x
for i in xrange(1, len(nums)):
cur = x - i
if cur in count:
flag[cur] = True
sub_count += 1
else:
break
sub_count += 1
res = max(res, sub_count)
return res

class Solution(object):
def longestConsecutive(self, nums):
"""
:type nums: List[int]
:rtype: int
"""
if len(nums) == 0: return 0
flag = { x:False for x in nums}#注意这里flag list comprehension的方法
res = 0
for x in nums:

if not flag[x]:
flag[x] = True
cur = x + 1
len1 = 0
while cur in flag and flag[cur] == False:
len1 += 1
flag[cur] = True#注意这个flag 要在cur += 1之前。
cur += 1

cur = x - 1
len2 = 0
while cur in flag and flag[cur] == False:
len2 += 1
flag[cur] = True#注意这个flag 要在cur -= 1之前。
cur -= 1
#print len1, len2
res = max(res, len1 + len2 + 1)
return res