LeetCode --- Longest Consecutive Sequence

题目链接

对unordered_set和set的内部实现还不了解，只知道前者是hash实现的，后者是用R-B-Tree实现。有时间需要读下源码。

附上代码：

 1 class Solution {  2 public:  3     int longestConsecutive(vector<int> &num) {  4         unordered_set<int> mynum(num.begin(), num.end());  5         // "max_len" holds the length of the longest consecutive sequence

 6         int max_len(0);  7         // "N" is the length of "num"

 8         unsigned int N(num.size());  9         // iterator every element of vector num

10         for (unsigned int i(0); i < N; i++) { 11             // "count" holds the maximum length of 12             // consecutive sequence that can be found 13             // by expanding from "num[i]" to the left and right

14             int count(0), tmp(num[i]); 15             while (mynum.find(tmp) != mynum.end()) { 16                 // erase "tmp" from set

17  mynum.erase(tmp); 18                 count++; 19                 // since "INT_MAX + 1 = INT_MIN" 20                 // we should not consider {INT_MAX-1, INT_MAX, INT_MIN} as consecutive sequence 

21                 if (tmp == INT_MAX) break; 22                 tmp++; 23  } 24             tmp = nu