376. Wiggle Subsequence.cpp

class Solution {
public:
    int wiggleMaxLength(vector<int>& nums) {
        int peak=1, valley=1;
        for(int i = 1; i < nums.size(); ++i){
            if(nums[i] > nums[i-1]) peak = valley + 1;
            else if(nums[i] < nums[i-1]) valley = peak + 1;
        }
        return max(peak , valley);
    }
};