LeetCode|Summary Ranges

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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”].

注意：有INT_MAX和INT_MIN，减法小心溢出，还有-INT_MIN也会溢出

class Solution {public:    vector<string> summaryRanges(vector<int>& nums) {        vector<string> res;        int len = nums.size(), cnt = 1;        if(len == 0) return res;        string str = int2str(nums[0]);        nums.push_back(nums[len-1] + 2); // add a termiator, abs(diff) = 2        for(int i = 1; i <= len; i++){            if( (long long)nums[i]-nums[i-1] == 1) {                cnt++;            } else {                if(cnt == 1) res.push_back(str);                else res.push_back(str + "->" + int2str(nums[i-1]));                cnt = 1;                str = int2str(nums[i]);            }        } return res;    }private:    string int2str(long long x){        if(x == 0) return "0";        bool isNeg = (x < 0);        if(x < 0) x = -x;        stack<char> s;        while(x != 0){            s.push(x%10+'0');            x /= 10;        }        string res;        if(isNeg) res = "-";        while(!s.empty()){            res += s.top();            s.pop();        } return res;    }};

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