collatz with go 1.22

go.mod

@@ -0,0 +1,3 @@
+module main
+
+go 1.22.2

main.go

@@ -0,0 +1,85 @@
+/*
+			Bedir T. Karaabalı
+			https://github.com/bdrtr
+			2025
+
+*/
+
+package main
+
+import (
+	"fmt"
+	"sync"
+)
+
+
+type Results struct {
+	n      uint64
+	steps  uint64
+	peak   uint64
+	xor    uint64
+}
+
+func collatzLenAndPeak(x uint64) (uint64, uint64) {
+	steps := uint64(0)
+	peak := x
+	n := x
+
+	for n != 1 {
+		if n&1 != 0 {
+			n = 3*n + 1
+		} else {
+			n >>= 1
+		}
+
+		if n > peak {
+			peak = n
+		}
+		steps++
+	}
+	return steps, peak
+}
+
+func main() {
+	n := uint64(1_000_000)
+	concurrency := 8
+	batchSize := n / uint64(concurrency)
+
+	results := make(chan Results, concurrency)
+	var wg sync.WaitGroup
+
+	for i := 0; i < concurrency; i++ {
+		wg.Add(1)
+		go func(start, end uint64) {
+			defer wg.Done();
+			var localresult Results;
+
+			for j := start; j < end; j++ {
+				steps, peak := collatzLenAndPeak(j)
+				if steps > localresult.steps {
+					localresult = Results{n: j, steps: steps, peak: peak, xor: 0}
+				}
+			}
+
+			results <- localresult
+		}(uint64(i)*batchSize+1, uint64((i+1))*batchSize)
+	}
+
+	wg.Wait()
+	close(results)
+
+	bestN := uint64(0)
+	bestSteps := uint64(0)
+	bestPeak := uint64(0)
+
+	for res := range results {
+
+		if res.steps > bestSteps {
+			bestSteps = res.steps
+			bestN = res.n
+			bestPeak = res.peak
+		}
+	}
+
+	fmt.Printf("Number with the longest Collatz sequence under %d is %d with %d steps and peak %d\n", n, bestN, bestSteps, bestPeak)
+}