将各个连续段长度获取出来，输出最大值即可

#include <algorithm>
#include <climits>
class Solution {
public:
    /**
     * 
     * @param num int整型vector 
     * @return int整型
     */
    int longestConsecutive(vector<int>& num) {
        // write code here
        sort(num.begin(),num.end());
        vector<int> arr;
        int count=1;
        int n=num.size();
        for(int i=1;i<n;i++){
            if(num[i]==num[i-1]+1){
                count++;
            }
            else if(num[i]-num[i-1]>1){
                arr.push_back(count);
                count=1;
            }
        }
        arr.push_back(count);
        return *max_element(arr.begin(),arr.end());
    }
};