Leetcode 貪心 Longest Consecutive Sequence

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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.

題意：最長連續序列
思路：貪心
複雜度：時間 O(n)，空間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; //要注意相等的情況else{_max = max(_max, count);pre = num[i];count = 1;}}return max(_max, count);}

Leetcode 貪心 Longest Consecutive Sequence