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);
}Leetcode 贪心 Longest Consecutive Sequence
原文：http://blog.csdn.net/zhengsenlie/article/details/39122085