Add old 2017 puzzle 3.

2017/3/3_test.go

@@ -0,0 +1,64 @@
+package main
+
+import "testing"
+
+func abs(i int) int {
+	if i < 0 {
+		return -i
+	}
+	return i
+}
+
+func TestSpiralIndex(t *testing.T) {
+	for _, ts := range []struct {
+		idx  int
+		x, y int
+	}{
+		{idx: 1, x: 0, y: 0},
+		{idx: 2, x: 1, y: 0},
+		{idx: 3, x: 1, y: 1},
+		{idx: 4, x: 0, y: 1},
+		{idx: 5, x: -1, y: 1},
+		{idx: 6, x: -1, y: 0},
+		{idx: 7, x: -1, y: -1},
+		{idx: 8, x: 0, y: -1},
+		{idx: 9, x: 1, y: -1},
+		{idx: 10, x: 2, y: -1},
+		{idx: 11, x: 2, y: 0},
+		{idx: 12, x: 2, y: 1},
+		{idx: 13, x: 2, y: 2},
+		{idx: 14, x: 1, y: 2},
+		{idx: 15, x: 0, y: 2},
+		{idx: 16, x: -1, y: 2},
+		{idx: 17, x: -2, y: 2},
+		{idx: 18, x: -2, y: 1},
+		{idx: 19, x: -2, y: 0},
+		{idx: 20, x: -2, y: -1},
+		{idx: 21, x: -2, y: -2},
+		{idx: 22, x: -1, y: -2},
+		{idx: 23, x: 0, y: -2},
+		{idx: 24, x: 1, y: -2},
+		{idx: 25, x: 2, y: -2},
+	} {
+		if x, y := spiralIndex(ts.idx); x != ts.x || y != ts.y {
+			t.Errorf("spiralIndex(%2d) = %2d,%2d; want %2d,%2d d %d", ts.idx, x, y, ts.x, ts.y, abs(ts.x)+abs(ts.y))
+		}
+	}
+}
+
+func TestStepCount(t *testing.T) {
+	t.Skip("Skipping until index code works")
+	for _, ts := range []struct {
+		cell int
+		want int
+	}{
+		{cell: 1, want: 0},
+		{cell: 12, want: 3},
+		{cell: 23, want: 2},
+		{cell: 1024, want: 31},
+	} {
+		if got := stepCount(ts.cell); got != ts.want {
+			t.Errorf("stepCount(%d) = %d; want %d", ts.cell, got, ts.want)
+		}
+	}
+}