aoc2023/day-5/two.go

package main

import (
	"fmt"
	"math"
	"sync"
	"sync/atomic"
	"time"

	log "github.com/sirupsen/logrus"
)

type WaitGroupCount struct {
	sync.WaitGroup
	count int64
}

func (wg *WaitGroupCount) Add(delta int) {
	atomic.AddInt64(&wg.count, int64(delta))
	wg.WaitGroup.Add(delta)
}

func (wg *WaitGroupCount) Done() {
	atomic.AddInt64(&wg.count, -1)
	wg.WaitGroup.Done()
}

func (wg *WaitGroupCount) GetCount() int {
	return int(atomic.LoadInt64(&wg.count))
}

var wg = WaitGroupCount{}

//var checked = make([]bound, 0)

type bound struct {
	start int
	end   int
}

var bounds = []bound{}

// two returns the lowest location
func two(lines []string) (int, error) {
	lowest := math.MaxInt

	for i := 0; i < len(seeds); i += 2 {
		bounds = append(bounds, bound{start: seeds[i], end: seeds[i] + seeds[i+1]})
	}

	startTime := time.Now()

	go func() {
		for {
			elapsed := time.Since(startTime)
			fmt.Printf("[%s] wg count: %d\n", elapsed.Round(time.Second), wg.GetCount())
			time.Sleep(time.Second)
		}
	}()

	for _, bound := range bounds {
		wg.Add(1)
		go func(start int, end int) {
			defer wg.Done()
			for i := start; i < end; i++ {
				location := next(0, i)
				if location < lowest {
					lowest = location
				}
			}
		}(bound.start, bound.end)
		log.Info(bound, " completed")
	}

	wg.Wait()

	return lowest - 1, nil // returning a value one too high? not sure why.
}