LeetCode:300. Longest Increasing Subsequence

Given an unsorted array of integers, find the length of longest increasing subsequence.

For example,
Given [10, 9, 2, 5, 3, 7, 101, 18],
The longest increasing subsequence is [2, 3, 7, 101], therefore the length is 4. Note that there may be more than one LIS combination, it is only necessary for you to return the length.

Your algorithm should run in O(n2) complexity.

Follow up: Could you improve it to O(n log n) time complexity?

这道题是我看人家博客如何深入浅出地讲动态规划时必举的例子，因此，直接上AC：

class Solution {public:    int lengthOfLIS(vector<int>& nums) {        vector<int> res;    for(int i=0; i<nums.size(); i++) {        auto it = std::lower_bound(res.begin(), res.end(), nums[i]);        if(it==res.end()) res.push_back(nums[i]);        else *it = nums[i];    }    return res.size();    }};