Data commit

Task/Constrained-random-points-on-a-circle/Rust/constrained-random-points-on-a-circle.rust

@@ -0,0 +1,71 @@
+extern crate rand;
+
+use rand::Rng;
+
+const POINTS_N: usize = 100;
+
+fn generate_point<R: Rng>(rng: &mut R) -> (i32, i32) {
+    loop {
+        let x = rng.gen_range(-15, 16); // exclusive
+        let y = rng.gen_range(-15, 16);
+
+        let r2 = x * x + y * y;
+        if r2 >= 100 && r2 <= 225 {
+            return (x, y);
+        }
+    }
+}
+
+fn filtering_method<R: Rng>(rng: &mut R) {
+    let mut rows = [[" "; 62]; 31];
+
+    // Generate points
+    for _ in 0..POINTS_N {
+        let (x, y) = generate_point(rng);
+        rows[(y + 15) as usize][(x + 15) as usize * 2] = "*";
+    }
+
+    // draw the points
+    for row in &rows {
+        println!("{}", row.concat());
+    }
+}
+
+fn precalculating_method<R: Rng>(rng: &mut R) {
+    // Generate all possible points
+    let mut possible_points = Vec::with_capacity(404);
+    for y in -15..=15 {
+        for x in -15..=15 {
+            let r2 = x * x + y * y;
+            if r2 >= 100 && r2 <= 225 {
+                possible_points.push((x, y));
+            }
+        }
+    }
+
+    // A truncated Fisher-Yates shuffle
+    let len = possible_points.len();
+    for i in (len - POINTS_N..len).rev() {
+        let j = rng.gen_range(0, i + 1);
+        possible_points.swap(i, j);
+    }
+
+    // turn the selected points into "pixels"
+    let mut rows = [[" "; 62]; 31];
+    for &(x, y) in &possible_points[len - POINTS_N..] {
+        rows[(y + 15) as usize][(x + 15) as usize * 2] = "*";
+    }
+
+    // draw the "pixels"
+    for row in &rows {
+        println!("{}", row.concat());
+    }
+}
+
+fn main() {
+    let mut rng = rand::weak_rng();
+
+    filtering_method(&mut rng);
+
+    precalculating_method(&mut rng);
+}