动态规划（最长递增子序列）---最长摆动子序列

最长摆动子序列

376. Wiggle Subsequence (Medium)

题目描述：

给定一个数组，求出其最长摆动子序列

Input: [1,7,4,9,2,5]Output: 6The entire sequence is a wiggle sequence.Input: [1,17,5,10,13,15,10,5,16,8]Output: 7There are several subsequences that achieve this length. One is [1,17,10,13,10,16,8].Input: [1,2,3,4,5,6,7,8,9]Output: 2

代码：

public int wiggleMaxLength(int []nums){if(nums==null||nums.length==0)return 0;int up=1;int down=1;for(int i=1;i<nums.length;i++){if(nums[i]>nums[i-1]){up=down+1;}else if(nums[i]<nums[i-1]){down=up+1;}} return Math.max(up,down);}