Given an unsorted array of integers,find the length of longest increasing subsequence.
Example:
Input: Output: 4 Explanation: The longest increasing subsequence is,therefore the length is . [10,9,2,5,3,7,101,18][2,101]4
Note:
- 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?
Solution:
Using dynamic programming and binary search,a[i] for the min last value of increasing subsequence of length i.
class Solution { public int lengthOfLIS(int[] nums) { int[] a = new int[nums.length]; int max_len = 0; for (int i = 0; i < nums.length; i++) { int index = Arrays.binarySearch(a,0,max_len,nums[i]); if (index < 0) { int p = -index-1; a[p] = nums[i]; if (p == max_len) max_len++; } } return max_len; } }