Leetcode 贪心 Longest Consecutive Sequence

Longest Consecutive Sequence

 Total Accepted: 19169 Total Submissions: 68303My Submissions

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.

题意：最长连续序列
思路：贪心
复杂度：时间 O(n)，空间O(1)

int longestConsecutive(vector<int> &num){if(num.empty()) return 0;int _max = 1;int count = 1;sort(num.begin(), num.end());for(int pre = num[0], i = 1; i < num.size(); ++i){if(num[i] == pre + count) count++;else if(num[i] == num[i - 1]) continue; //要注意相等的情况else{_max = max(_max, count);pre = num[i];count = 1;}}return max(_max, count);}