Leetcode--Longest Consecutive Sequence

Given an unsorted array of integers, find the length of the longest consecutive elements sequence.

For example,

Given 

[100, 4, 200, 1, 3, 2]

,

The longest consecutive elements sequence is 

[1, 2, 3, 4]

. Return its length: 

4

.

Your algorithm should run in O(n) complexity.

思路：

首先对给定的数组排序，如果当前的元素值比前一个值大一，则长度加一。再判断是否长度值是否大于当前的最大值，大于则更新最大值。

这里需要注意的是重复的数，所做的处理是继续下面的判断

class Solution {
public:
    int longestConsecutive(vector<int> &num) {
        if(num.size()<=0)
            return 0;
        else if(num.size()==1)
            return 1;
        sort(num.begin(),num.end());
        int temp=1;
        int max=1;
        for(int i=1;i<num.size();i++)
        {
            if(num[i]-num[i-1]==1)
            {
                temp++;
                
            }
            else if(num[i]-num[i-1]==0)
                continue;
            else
            {
                if(temp>max)
                    max=temp;
                temp=1;
            }
        }
        if(temp>max)
            max=temp;
        return max;
    }
};