Added rust implementation of the jarvis march algorithm

Added rust implementation of the jarvis march algorithm

Author: jdonszelmann

CONTRIBUTORS.md

@@ -51,3 +51,4 @@ This file lists everyone, who contributed to this repo and wanted to show up her
 - Vincent Zalzal
 - Jonathan D B Van Schenck
 - James Goytia
+- Jonathan Dönszelmann

contents/jarvis_march/code/rust/jarvis_march.rs

@@ -0,0 +1,65 @@
+
+// Define a point to be a tuple of two integers
+type Point = (i64, i64);
+
+// Is the turn counter clockwise?
+fn turn_counter_clockwise(p1: Point, p2: Point, p3: Point) -> bool {
+    (p3.1 - p1.1) * (p2.0 - p1.0) >= (p2.1 - p1.1) * (p3.0 - p1.0)
+}
+
+fn jarvis_march(gift: Vec<Point>) -> Option<Vec<Point>> {
+    // There can only be a convex hull if there are more than 2 points
+    if gift.len() < 3 {
+        return None;
+    }
+
+    let leftmost_point = gift
+        // Iterate over all points
+        .iter()
+        .cloned()
+        // Find the point with minimum x
+        .min_by_key(|i| i.0)
+        // If there are no points in the gift, there might
+        // not be a minimum. Unwrap fails (panics) the program
+        // if there wasn't a minimum, but we know there always
+        // is because we checked the size of the gift.
+        .unwrap();
+
+    let mut hull = vec![leftmost_point];
+
+    let mut point_on_hull = leftmost_point;
+    loop {
+        // Search for the next point on the hull
+        let mut endpoint = gift[0];
+        for i in 1..gift.len() {
+            if endpoint == point_on_hull || !turn_counter_clockwise(gift[i], hull[hull.len() - 1], endpoint) {
+                endpoint = gift[i];
+            }
+        }
+
+        point_on_hull = endpoint;
+
+        // Stop whenever we got back to the same point
+        // as we started with, and we wrapped the gift
+        // completely.
+        if hull[0] == endpoint {
+            break;
+        } else {
+            hull.push(point_on_hull);
+        }
+    }
+
+    Some(hull)
+}
+
+fn main() {
+    let test_gift = vec![
+        (-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)
+    ];
+
+    let hull = jarvis_march(test_gift);
+
+    println!("The points in the hull are: {:?}", hull);
+}

contents/jarvis_march/jarvis_march.md

@@ -48,6 +48,8 @@ Since this algorithm, there have been many other algorithms that have advanced t
 [import, lang:"go"](code/golang/jarvis.go)
 {% sample lang="v" %}
 [import, lang:"v"](code/v/jarvis.v)
+{% sample lang="rust" %}
+[import, lang:"rust"](code/rust/jarvis_march.rs)
 {% endmethod %}
 
 <script>