标签：
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.
===================
给一个未排序数组,找到一个最长的连续数组,返回其长度.
====
思路:
利用一个hash表,存储已经扫描的数组元素,
对数组中每一个curr元素,都必须在hash表中向前查找,向后查找.
===
code:
class Solution { public: int longestConsecutive(vector<int>& nums) { unordered_map<int,bool> hash_used; for(auto i:nums){ hash_used[i] = false; } int longest = 0; for(auto i:nums){ if(hash_used[i]) continue; int length = 1; hash_used[i] = true; for(int j = i+1;hash_used.find(j)!=hash_used.end();j++){ hash_used[j] = true; length++; } for(int j = i-1;hash_used.find(j)!=hash_used.end();j--){ hash_used[j] = true; length++; } longest = max(longest,length); }//for return longest; } };
128. Longest Consecutive Sequence
标签：
原文地址：http://www.cnblogs.com/li-daphne/p/5621895.html
