LC 1499. Max Value of Equation

link

class Solution {
public:
    int findMaxValueOfEquation(vector<vector<int>>& points, int k) {
        deque<int> dq;
        int n=points.size();
        int res=INT_MIN;
        for(int i=0;i<n;i++){
            while(!dq.empty() && points[i][0]-points[dq.front()][0]>k) dq.pop_front();
            if(dq.empty()){
                dq.push_back(i);
                continue;
            }
            res=max(res,points[i][0]+points[i][1]+points[dq.front()][1]-points[dq.front()][0]);
            while(!dq.empty() && points[i][1]-points[i][0]>points[dq.back()][1]-points[dq.back()][0]) dq.pop_back();
            dq.push_back(i);
        }
        return res;
    }
};