Missing Range
要点：题简单，这类题的特点都是记录上一步的状态，比如这题是end
错误点：
- 三种情况：一是连续的，即和上一个end差1，而是中间只差1个数，没有’->'，最后是大于1，有’->'
- 看清题：upper/lower是boundary，不一定出现在nums里。为了统一，把upper+1放入nums，同时初始end=lower-1
- 区间是[end+1, num-1]
- 别忘了每次更新end
# Given a sorted integer array where the range of elements are [lower, upper] inclusive, return its missing ranges.
# For example, given [0, 1, 3, 50, 75], lower = 0 and upper = 99, return ["2", "4->49", "51->74", "76->99"].
# Hide Company Tags Google
# Hide Tags Array
# Hide Similar Problems (M) Summary Ranges
class Solution(object):
def findMissingRanges(self, nums, lower, upper):
"""
:type nums: List[int]
:type lower: int
:type upper: int
:rtype: List[str]
"""
end = lower
res = []
for num in nums+[upper+1]:
if num!=end:
if num-1!=end:
res.append("{}->{}".format(end, num-1))
else:
res.append(str(num-1))
end = num+1 # error: don't forget
return res
sol = Solution()
assert sol.findMissingRanges([0, 1, 3, 50, 75], 0, 99)==['2', '4->49', '51->74', '76->99']