Solution

point.go

package main

import (
	"math"
)

type Point struct {
	Val float64
	Ts  uint32
}

func Fix(in []Point, from, to, interval uint32) []Point {
	var res []Point
	for i := from; i < to; i += interval {
		v := (i / interval) * interval
		if i%interval != 0 {
			res = append(res, find(in, v+interval))
			continue
		}
		res = append(res, find(in, v))
	}
	return res
}

func find(in []Point, ts uint32) Point {
	for _, p := range in {
		if p.Ts == ts {
			return p
		}
	}
	return Point{math.NaN(), ts}
}