
You are given an array points containing the coordinates of points on a 2D plane, sorted by the x-values, where points[i] = [x _i , y _i ] such that x _i < x _j for all 1 <= i < j <= points.length . You are also given an integer k .
Return the maximum value of the equation y _i + y _j + |x _i - x _j | where |x _i - x _j | <= k and 1 <= i < j <= points.length .
It is guaranteed that there exists at least one pair of points that satisfy the constraint |x _i - x _j | <= k .
2 <= points.length <= 10 ^5points[i].length == 2-10 ^8 <= x _i , y _i <= 10 ^80 <= k <= 2 * 10 ^8x _i < x _j for all 1 <= i < j <= points.lengthx _i form a strictly increasing sequence.