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.

// https://oj.leetcode.com/problems/longest-consecutive-sequence/// Author : Chao Zeng// Date : 2015-3-30class Solution {public:int longestConsecutive(vector<int> &num) {map<int,int> mp;const int NUM = 100;//由于数据中存在负数，所以数组元素加一个偏移量，，保证数组下标有效性int length = num.size();for (int i = 0; i < length; i++){mp[num[i] + NUM] = 1;}int ans;int res = 0;for (int i = 0; i < length; i++){ans = 1;if (mp.count(num[i] + NUM)){int left = num[i] + NUM – 1;while (mp.count(left) && mp[left] != 0){mp[left–] = 0;ans++;}int right = num[i] + NUM + 1;while (mp.count(right) && mp[right] != 0){mp[right++] = 0;ans++;}}if (res < ans){res = ans;}}return res;}};

赚钱之道很多，但是找不到赚钱的种子，便成不了事业家。