Add solution for cw-compare-margin

cw-compare-margin/README.md

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+# Compare within margin
+
+Create a function `close_compare` that accepts 3 parameters: `a`, `b`, and an optional `margin`. The function should return whether `a` is lower than, close to, or higher than `b`.
+
+Please note the following:
+
+- When `a` is close to `b`, return `0`.
+    - For this challenge, `a` is considered "close to" `b` if `margin` is greater than or equal to the absolute distance between `a` and `b`.
+
+Otherwise...
+
+- When `a` is less than `b`, return `-1`.
+
+- When `a` is greater than `b`, return `1`.
+
+
+If `margin` is not given, treat it as if it were zero.
+
+Assume: `margin >= 0`
+
+---
+
+### Example 1
+
+If `a = 3`, `b = 5`, and `margin = 3`, then `close_compare(a, b, margin)` should return `0`.
+
+This is because `a` and `b` are no more than 3 numbers apart.
+
+### Example 2
+
+If `a = 3`, `b = 5`, and `margin = 0`, then `close_compare(a, b, margin)` should return `-1`.
+
+This is because the distance between `a` and `b` is greater than 0, and `a` is less than `b`.

cw-compare-margin/go.mod

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+module github.com/skosovsky/algo/cw-compare-margin

cw-compare-margin/main.go

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+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	fmt.Println(closeCompare(4.0, 5.0, 0.0)) //nolint:gomnd
+}
+
+func closeCompare(a, b, margin float64) int {
+	sub := a - b // или math.Abs(a-b), тогда упрощение в if
+
+	if (sub <= 0 && sub >= (0-margin)) || (sub >= 0 && sub <= margin) {
+		return 0
+	} else if a < b {
+		return -1
+	}
+
+	return 1
+}
+
+func closeCompareClever(a, b, margin float64) int {
+	switch {
+	case a-b > margin:
+		return 1
+	case b-a > margin:
+		return -1
+	default:
+		return 0
+	}
+}

cw-compare-margin/main_test.go

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+package main
+
+import "testing"
+
+func Test_closeCompare(t *testing.T) {
+	type args struct {
+		a      float64
+		b      float64
+		margin float64
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{
+			name: "Example 1",
+			args: args{4.0, 5.0, 0.0},
+			want: -1,
+		},
+		{
+			name: "Example 2",
+			args: args{5.0, 5.0, 0.0},
+			want: 0,
+		},
+		{
+			name: "Example 3",
+			args: args{6.0, 5.0, 0.0},
+			want: 1,
+		},
+		{
+			name: "Example 4",
+			args: args{2.0, 5.0, 3.0},
+			want: 0,
+		},
+		{
+			name: "Example 5",
+			args: args{5.0, 5.0, 3.0},
+			want: 0,
+		},
+		{
+			name: "Example 6",
+			args: args{8.0, 5.0, 3.0},
+			want: 0,
+		},
+		{
+			name: "Example 7",
+			args: args{8.1, 5.0, 3.0},
+			want: 1,
+		},
+		{
+			name: "Example 8",
+			args: args{1.99, 5.0, 3.0},
+			want: -1,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := closeCompare(tt.args.a, tt.args.b, tt.args.margin); got != tt.want {
+				t.Errorf("closeCompare() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}