Summary Ranges

题目：

Given a sorted integer array without duplicates, return the summary of its ranges.

For example, given

[0,1,2,4,5,7]

, return

["0->2","4->5","7"].

解题思路：
class Solution:

# @param {integer[]} nums

# @return {string[]}

def summaryRanges(self, nums):

ans = []

i = 0

while i<len(nums):

if i<len(nums)-1 and 1==nums[i+1]-nums[i]:

start = nums[i]

j = i+1

while(j<len(nums) and nums[j]-nums[i]==1):

i += 1

j += 1

end = nums[j-1]

ans.append(str(start)+"->"+str(end))

i = j

else:

ans.append(str(nums[i]))

i += 1

return ans