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?
解法一:
借鉴了之前increasing triplet sequence的思路。
class Solution { public: int lengthOfLIS(vector<int>& nums) { if(nums.size()<1) return 0; vector<int> seq(1,INT_MAX); for(int i=0; i< nums.size(); i++){ for(int j=0; j<seq.size(); j++){ if(nums[i]<=seq[j]){ seq.erase(seq.begin()+j); seq.insert(seq.begin()+j,nums[i]); break; } } if(nums[i]>seq.back()) seq.push_back(nums[i]); } return seq.size(); } };