Summary Ranges

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"].

class Solution {
public:
vector<string> summaryRanges(vector<int>& nums) {
vector<string> res;
if (nums.empty()) {
return res;
}
int begin = 0, end = 1;
while (begin < nums.size()) {
if ((end < nums.size() && nums[end] != nums[end - 1] + 1) || end == nums.size()) {
string range;
if (end - begin == 1) {
range = to_string(nums[begin]);
} else {
range = to_string(nums[begin]) + "->" + to_string(nums[end - 1]);
}
res.push_back(range);
begin = end;
}
end++;
}

return res;
}
};