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.
class Solution { public: int longestConsecutive(vector<int> &num) { set<int> s(num.begin(), num.end()); auto it = s.begin(); int c = 1; int l = 1; int prev = *it; for(++it; it!=s.end();it++){ if(*it == prev+1){ c++; } else{ l = max(l, c); c = 1; } prev = *it; } return max(l,c); } };
原文：http://www.cnblogs.com/code-swan/p/4140754.html