376. Wiggle Subsequence

代码

class Solution {
public:
    int wiggleMaxLength(vector<int>& nums) {
        int n = nums.size();
        int res = 1;
        int prediff = 0;
        int curdiff = 0;
        for(int i = 0;i < n-1;i++){
            curdiff = nums[i+1] - nums[i];
            if( (prediff >= 0 && curdiff < 0) ||
                (prediff <= 0 && curdiff > 0)){
                    res++;
                    prediff = curdiff;
                }
        }
        return res;
    }
};