Merge a103de7 into 7479a3e

README.md

@@ -109,3 +109,4 @@ problems from
 * [Day 97](https://github.com/vaskoz/dailycodingproblem-go/issues/203)
 * [Day 98](https://github.com/vaskoz/dailycodingproblem-go/issues/204)
 * [Day 99](https://github.com/vaskoz/dailycodingproblem-go/issues/205)
+* [Day 100](https://github.com/vaskoz/dailycodingproblem-go/issues/209)

day100/problem.go

@@ -0,0 +1,39 @@
+package day100
+
+// Point is a X and Y coordinate.
+type Point struct {
+	X, Y int
+}
+
+// MinimumStepsPath returns the minimum number of steps required
+// to walk the path. The path must be walked in order.
+// 8 directions possible: 4 cardinal and 4 intercardinal.
+func MinimumStepsPath(path []Point) int {
+	if len(path) < 2 {
+		return 0
+	}
+	steps := 0
+	current := path[0]
+	for i := 1; i < len(path); i++ {
+		next := path[i]
+		dx, dy := delta(current, next)
+		if dx < dy {
+			steps += dy
+		} else {
+			steps += dx
+		}
+		current = next
+	}
+	return steps
+}
+
+func delta(from, to Point) (int, int) {
+	return abs(to.X - from.X), abs(to.Y - from.Y)
+}
+
+func abs(x int) int {
+	if x < 0 {
+		return -x
+	}
+	return x
+}

day100/problem_test.go

@@ -0,0 +1,32 @@
+package day100
+
+import "testing"
+
+var testcases = []struct {
+	path         []Point
+	minimumSteps int
+}{
+	{[]Point{{0, 0}, {1, 1}, {1, 2}}, 2},
+	{[]Point{}, 0},
+	{nil, 0},
+	{[]Point{{100, 100}}, 0},
+	{[]Point{{0, 0}, {-10, -10}, {20, 20}}, 40},
+	{[]Point{{0, 0}, {-10, -10}, {20, 40}}, 60},
+}
+
+func TestMinimumStepsPath(t *testing.T) {
+	t.Parallel()
+	for _, tc := range testcases {
+		if steps := MinimumStepsPath(tc.path); steps != tc.minimumSteps {
+			t.Errorf("Expected %v got %v", tc.minimumSteps, steps)
+		}
+	}
+}
+
+func BenchmarkMinimumStepsPath(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tc := range testcases {
+			MinimumStepsPath(tc.path)
+		}
+	}
+}