Add fisher yates shuffle (rust-lang#394)

Author: jerr-it

src/general/fisher_yates_shuffle.rs

@@ -0,0 +1,25 @@
+use std::time::{SystemTime, UNIX_EPOCH};
+
+use crate::math::PCG32;
+
+const DEFAULT: u64 = 4294967296;
+
+fn gen_range(range: usize, generator: &mut PCG32) -> usize {
+    generator.get_u64() as usize % range
+}
+
+pub fn fisher_yates_shuffle(array: &mut [i32]) {
+    let seed = match SystemTime::now().duration_since(UNIX_EPOCH) {
+        Ok(duration) => duration.as_millis() as u64,
+        Err(_) => DEFAULT,
+    };
+
+    let mut random_generator = PCG32::new_default(seed);
+
+    let len = array.len();
+
+    for i in 0..(len - 2) {
+        let r = gen_range(len - i, &mut random_generator);
+        array.swap(i, i + r);
+    }
+}

src/general/mod.rs

@@ -1,11 +1,13 @@
 mod convex_hull;
+mod fisher_yates_shuffle;
 mod hanoi;
 mod huffman_encoding;
 mod kmeans;
 mod nqueens;
 mod two_sum;
 
 pub use self::convex_hull::convex_hull_graham;
+pub use self::fisher_yates_shuffle::fisher_yates_shuffle;
 pub use self::hanoi::hanoi;
 pub use self::huffman_encoding::{HuffmanDictionary, HuffmanEncoding};
 pub use self::kmeans::f32::kmeans as kmeans_f32;