题目描述：
Given a sorted integer array without duplicates, return the summary of its ranges.
Example 1:
Input: [0,1,2,4,5,7]
Output: ["0->2","4->5","7"]
Explanation: 0,1,2 form a continuous range; 4,5 form a continuous range.
Example 2:
Input: [0,2,3,4,6,8,9]
Output: ["0","2->4","6","8->9"]
Explanation: 2,3,4 form a continuous range; 8,9 form a continuous range.给定一个有序数组，返回连续数字组成的区间。遍历一遍数组，如果当前数字能和上一个区间合并，那么更新这个区间的终点，否则新建一个区间。
class Solution {
public:
vector<string> summaryRanges(vector<int>& nums) {
vector<string> result;
if(nums.size()==0) return result;
vector<vector<int>> v(1,vector<int>(1,nums[0]));
for(int i=1;i<nums.size();i++)
{
if(nums[i]==v.back().back()+1) v.back().push_back(nums[i]);
else v.push_back(vector<int>(1,nums[i]));
}
for(int i=0;i<v.size();i++)
{
if(v[i].size()==1) result.push_back(to_string(v[i][0]));
else result.push_back(to_string(v[i][0])+"->"+to_string(v[i].back()));
}
return result;
}
};