https://leetcode.com/problems/longest-increasing-subsequence/
题意
- 双重遍历，复杂度$O(n^2)$
- 动态规划，以nums[i]结束的最大递增序列，即从nums[i]向前遍历，如果nums[j]小于nums[i]那么nums[i]=Math.max(nums[i], nums[j] + 1)
```java
class Solution {
public int lengthOfLIS(int[] nums) {
}if (nums == null || nums.length == 0) { return 0; } int max = 1; int dp[] = new int[nums.length]; Arrays.setAll(dp, new IntUnaryOperator() { @Override public int applyAsInt(int operand) { return 1; } }); for (int i = 0; i < nums.length; i++) { for (int j = i - 1; j >= 0; j--) { if (nums[i] > nums[j]) { dp[i] = Math.max(dp[i], dp[j] + 1); } max = Math.max(max, dp[i]); } } return max;
}
```