add the jarvis march in go

contents/jarvis_march/code/golang/jarvis.go

@@ -0,0 +1,68 @@
+package main
+
+import (
+	"fmt"
+)
+
+type point struct {
+	x, y float64
+}
+
+func leftMostPoint(points []point) point {
+	ret := points[0]
+
+	for _, p := range points {
+		if (p.x < ret.x) || (p.x == ret.x && p.y < ret.y) {
+			ret = p
+		}
+	}
+
+	return ret
+}
+
+func (p point) equal(o point) bool {
+	return p.x == o.x && p.y == o.x
+}
+
+func counterClockWise(p1, p2, p3 point) bool {
+	return (p3.y-p1.y)*(p2.x-p1.x) >= (p2.y-p1.y)*(p3.x-p1.x)
+}
+
+func jarvisMarch(points []point) []point {
+	hullPoints := make([]point, 0)
+	hullPoint := leftMostPoint(points)
+	hullPoints = append(hullPoints, hullPoint)
+
+	for {
+		endPoint := points[0]
+
+		for _, p := range points[1:] {
+			if endPoint.equal(hullPoint) || !counterClockWise(p, hullPoints[len(hullPoints)-1], endPoint) {
+				endPoint = p
+			}
+		}
+
+		hullPoint = endPoint
+
+		if endPoint.equal(hullPoints[0]) {
+			break
+		}
+
+		hullPoints = append(hullPoints, hullPoint)
+	}
+	return hullPoints
+}
+
+func main() {
+	points := []point{{-5, 2}, {5, 7}, {-6, -12}, {-14, -14}, {9, 9},
+		{-1, -1}, {-10, 11}, {-6, 15}, {-6, -8}, {15, -9},
+		{7, -7}, {-2, -9}, {6, -5}, {0, 14}, {2, 8},
+	}
+
+	hullPoints := jarvisMarch(points)
+	fmt.Println("The hull points are:")
+
+	for _, p := range hullPoints {
+		fmt.Printf("x=%f y=%f\n", p.x, p.y)
+	}
+}

contents/jarvis_march/jarvis_march.md

@@ -40,6 +40,8 @@ Since this algorithm, there have been many other algorithms that have advanced t
 [import, lang:"python"](code/python/jarvisMarch.py)
 {% sample lang="cpp" %}
 [import, lang:"c_cpp"](code/c++/jarvis_march.cpp)
+{% sample lang="go" %}
+[import, lang:"go"](code/golang/jarvis.go)
 {% endmethod %}
 
 <script>