Added sort colors solution.

README.md

@@ -135,6 +135,7 @@ other languages.
 - Sum Root to Leaf (https://leetcode.com/problems/sum-root-to-leaf-numbers)
 - Repeated DNA Sequence (https://leetcode.com/problems/repeated-dna-sequences/)
 - Rotate Array (https://leetcode.com/problems/rotate-array/)
+- Sort Colors (https://leetcode.com/problems/sort-colors)
 
 ### Other
 

src/leetcode/mod.rs

@@ -40,3 +40,4 @@ mod third_max;
 mod two_sum;
 mod unique_occurrences;
 mod zero_or_one;
+mod sort_colors;

src/leetcode/sort_colors.rs

@@ -0,0 +1,40 @@
+pub fn sort_colors(numbers: &mut [i32]) {
+    let counts = numbers.iter().fold((0, 0, 0), |mut acc, curr| {
+        match curr {
+            0 => acc.0 += 1,
+            1 => acc.1 += 1,
+            2 => acc.2 += 1,
+            _ => {}
+        }
+        acc
+    });
+
+    let mut index = 0;
+    for _ in 0..counts.0 {
+        numbers[index] = 0;
+        index += 1;
+    }
+    for _ in 0..counts.1 {
+        numbers[index] = 1;
+        index += 1;
+    }
+    for _ in 0..counts.2 {
+        numbers[index] = 2;
+        index += 1;
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::vec;
+
+    use crate::leetcode::sort_colors::sort_colors;
+
+    #[test]
+    fn test_sort_colors() {
+        let mut numbers = vec![0, 1, 2, 0, 1, 2];
+        sort_colors(&mut numbers);
+
+        assert_eq!(&vec![0, 0, 1, 1, 2, 2], &numbers);
+    }
+}