Fixing a few places where I was using "crypto/rand"

to use "math/rand" with a proper seeding instead.

algs4/src/go/algs4-flips/main.go

@@ -1,12 +1,12 @@
 package main
 
 import (
-	"crypto/rand"
 	"fmt"
 	"math"
-	"math/big"
+	"math/rand"
 	"os"
 	"strconv"
+	"time"
 )
 
 import (
@@ -21,7 +21,9 @@ func main() {
 		os.Exit(1)
 	}
 
-	nflips, err := strconv.ParseInt(os.Args[1], 10, 32)
+	rand.Seed(time.Now().UTC().UnixNano())
+
+	nflips, err := strconv.Atoi(os.Args[1])
 	if err != nil {
 		fmt.Println("Wat.", err)
 		os.Exit(2)
@@ -30,16 +32,8 @@ func main() {
 	heads := algs4.NewCounter("heads")
 	tails := algs4.NewCounter("tails")
 
-	randMax := big.NewInt(2)
-
-	for t := int64(0); t < nflips; t += int64(1) {
-		n, err := rand.Int(rand.Reader, randMax)
-		if err != nil {
-			fmt.Println("Ugh:", err)
-			os.Exit(4)
-		}
-
-		if n.Int64() < 1 {
+	for t := 0; t < nflips; t++ {
+		if rand.Float64() > 0.5 {
 			heads.Increment()
 		} else {
 			tails.Increment()

algs4/src/go/algs4/rolls.go

@@ -1,32 +1,21 @@
 package algs4
 
 import (
-	"crypto/rand"
 	"fmt"
-	"math/big"
 )
 
 const ROLL_SIDES = 6
 
 func Rolls(nrolls int64) ([]*Counter, error) {
-	var err error
-
 	rolls := make([]*Counter, ROLL_SIDES+1)
 	for i := 1; i <= ROLL_SIDES; i += 1 {
 		rolls[i] = NewCounter(fmt.Sprintf("%d's", i))
 	}
 
-	var result *big.Int
-	randMax := big.NewInt(ROLL_SIDES)
+	randMax := float64(ROLL_SIDES)
 
-	for t := int64(0); t < nrolls; t += 1 {
-		result, err = rand.Int(rand.Reader, randMax)
-
-		if err != nil {
-			return nil, err
-		}
-
-		rolls[int(result.Int64())+1].Increment()
+	for t := int64(0); t < nrolls; t++ {
+		rolls[int(RandomUniform(float64(0.0), randMax))+1].Increment()
 	}
 
 	return rolls, nil