42: coded triangle numbers

42_coded_triangle_numbers/main.go

@@ -0,0 +1,63 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"strings"
+)
+
+const BASE = 64
+
+func main() {
+	b, err := ioutil.ReadFile("p042_words.txt")
+	if err != nil {
+		panic(err)
+	}
+
+	word := readWords(string(b))
+	count := 0
+	for _, w := range word {
+		if isTriangleNumber(worthOf(w)) {
+			count++
+		}
+	}
+	fmt.Println("count:", count)
+}
+
+func readWords(s string) []string {
+	if len(s) == 0 {
+		return nil
+	}
+	str := strings.Replace(s, "\"", "", -1)
+	ret := strings.Split(str, ",")
+	return ret
+}
+
+func worthOf(word string) int {
+	if len(word) == 0 {
+		return 0
+	}
+	sum := 0
+	for i := 0; i < len(word); i++ {
+		a := word[i : i+1][0]
+		w := uint8(a) - BASE
+		sum += int(w)
+	}
+	return sum
+}
+
+func isTriangleNumber(n int) bool {
+	//tn = ½n(n+1)
+	x := 2 * n
+	res := x
+	//牛顿法求平方根
+	for res*res > x {
+		res = (res + x/res) / 2
+	}
+	for i := res; i > 0; i-- {
+		if i*(i+1) == x {
+			return true
+		}
+	}
+	return false
+}

42_coded_triangle_numbers/main_test.go

@@ -0,0 +1,97 @@
+package main
+
+import (
+	"reflect"
+	"testing"
+)
+
+func Test_readWords(t *testing.T) {
+	type args struct {
+		s string
+	}
+	tests := []struct {
+		name string
+		args args
+		want []string
+	}{
+		{
+			"empty_input",
+			args{""},
+			nil,
+		},
+		{
+			"one_name",
+			args{"\"VIC\""},
+			[]string{"VIC"},
+		},
+		{
+			"two_names",
+			args{"\"VIC\",\"COCO\""},
+			[]string{"VIC", "COCO"},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := readWords(tt.args.s); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("readWords() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_worthOf(t *testing.T) {
+	tt := []struct {
+		name string
+		word string
+		want int
+	}{
+		{
+			"COLIN",
+			"COLIN",
+			53,
+		},
+	}
+
+	for _, tc := range tt {
+		t.Run(tc.name, func(t *testing.T) {
+			got := worthOf(tc.word)
+			if got != tc.want {
+				t.Errorf("worthOf() = %d, want %d", got, tc.want)
+			}
+		})
+	}
+}
+
+func Test_isTriangleNumber(t *testing.T) {
+	type args struct {
+		n int
+	}
+	tests := []struct {
+		name string
+		args args
+		want bool
+	}{
+		{
+			"1",
+			args{1},
+			true,
+		},
+		{
+			"28",
+			args{28},
+			true,
+		},
+		{
+			"29",
+			args{29},
+			false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := isTriangleNumber(tt.args.n); got != tt.want {
+				t.Errorf("isTriangleNumber() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}