标签:right nums int list subsequence longest increasing left
300. Longest Increasing Subsequence MediumGiven an integer array nums
, return the length of the longest strictly increasing subsequence.
A subsequence is a sequence that can be derived from an array by deleting some or no elements without changing the order of the remaining elements. For example, [3,6,2,7]
is a subsequence of the array [0,3,1,6,2,2,7]
.
Example 1:
Input: nums = [10,9,2,5,3,7,101,18] Output: 4 Explanation: The longest increasing subsequence is [2,3,7,101], therefore the length is 4.
Example 2:
Input: nums = [0,1,0,3,2,3] Output: 4
Example 3:
Input: nums = [7,7,7,7,7,7,7] Output: 1
Constraints:
1 <= nums.length <= 2500
-104 <= nums[i] <= 104
Follow up: Can you come up with an algorithm that runs in O(n log(n))
time complexity?
解法1:
class Solution { public int lengthOfLIS(int[] nums) { int[] dp = new int[nums.length]; int result = 1; Arrays.fill(dp, 1); for(int i=0;i<nums.length-1;i++){ for(int j=i+1;j<nums.length;j++){ if(nums[i] < nums[j]) dp[j] = Math.max(dp[j], dp[i]+1); result = Math.max(result, dp[j]); } } return result; } }
时间复杂度: O(N2)
解法2:
class Solution { public int lengthOfLIS(int[] nums) { List<Integer> list = new ArrayList(); for(int i=0;i<nums.length;i++){ int pos = binarySearch(list, nums[i]); if(pos >= list.size()) list.add(nums[i]); else list.set(pos, nums[i]); } return list.size(); } private int binarySearch(List<Integer> list, int target){ int left = 0,right = list.size(); while(left < right){ int mid = left+(right-left)/2; if(list.get(mid) >= target) right = mid; else left = mid+1; } return left; } }
时间复杂度:O(NlogN)
标签:right,nums,int,list,subsequence,longest,increasing,left 来源: https://www.cnblogs.com/cynrjy/p/16598307.html
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