```
public class Solution {
public int wiggleMaxLength(int[] nums) {
int n = nums.length;
if (n == 0)
return 0;
else if (n == 1)
return 1;
int len = 1;
int comp = 0; // 1: increasing, 0: equal, -1: decreasing
for (int i = 1; i < n; i++) {
if (nums[i] > nums[i-1]) {
if (comp == -1 || comp == 0)
len++;
comp = 1;
} else if (nums[i] < nums[i-1]) {
if (comp == 1 || comp == 0)
len++;
comp = -1;
}
}
return len;
}
}
```