376. 摆动序列

class Solution {
public:
    int wiggleMaxLength(vector<int>&v) {
        //
        auto tail = unique(v.begin(),v.end());
        v.erase(tail,v.end());
        //
        if(v.size()<=2)return v.size();
        int cnt = 0;
        for (int i = 1; i < v.size() - 1; i ++ ) {
            int pdir = v[i] - v[i-1];
            int cdir = v[i+1] - v[i];
            cnt += pdir*cdir<0?1:0;
        }
        return cnt+2;
    }
};

去重之后就不用考虑这么多复杂的情况