add fraction maths (issue #293)

Cargo.lock

@@ -13,18 +13,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
 [[package]]
-name = "dice-stats"
+name = "empty-zeros"
 version = "0.1.0"
-dependencies = [
- "itertools",
- "rand",
-]
-
-[[package]]
-name = "either"
-version = "1.8.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7fcaabb2fef8c910e7f4c7ce9f67a1283a1715879a7c230ca9d6d1ae31f16d91"
 
 [[package]]
 name = "fraction-math"
@@ -41,15 +31,6 @@ dependencies = [
  "wasi",
 ]
 
-[[package]]
-name = "itertools"
-version = "0.10.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b0fd2260e829bddf4cb6ea802289de2f86d6a7a690192fbe91b3f46e0f2c8473"
-dependencies = [
- "either",
-]
-
 [[package]]
 name = "libc"
 version = "0.2.139"

Cargo.toml

@@ -1,6 +1,7 @@
 [workspace]
 members = [
   "balance",
+  "empty-zeros",
   "fraction-math",
   "parens",
   "repeated-groups",

empty-zeros/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "empty-zeros"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

empty-zeros/src/main.rs

@@ -0,0 +1,77 @@
+/// Given a non-empty array containing only non-negative integers, return the
+/// list with trailing and leading zeroes removed.
+///
+/// Example:
+///
+/// ```
+/// > removeZeroes([0, 0, 0, 3, 1, 4, 1, 5, 9, 0, 0, 0, 0])
+/// > [3, 1, 4, 1, 5, 9]
+///
+/// > removeZeroes([0, 0, 0])
+/// > []
+///
+/// > removeZeroes([8])
+/// > [8]
+/// ```
+
+fn main() {
+    let mut v = vec![0, 0, 0, 3, 1, 4, 1, 5, 9, 0, 0, 0, 0];
+    println!("{:?}", remove_zeros(&mut v));
+    println!("{:?}", v);
+}
+
+fn remove_zeros(v: &mut Vec<usize>) {
+    if v.len() == 0 {
+        return;
+    }
+
+    let mut i = 0;
+    while i <= v.len() && v[0..i].iter().sum::<usize>() == 0 {
+        i += 1;
+    }
+
+    v.drain(..i - 1);
+
+    if v.len() == 0 {
+        return;
+    }
+
+    let mut j = v.len() - 1;
+    while v[j..].iter().sum::<usize>() == 0 {
+        j -= 1;
+    }
+
+    v.drain(j + 1..);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_remove_zeros() {
+        let mut v = vec![0, 0, 0, 3, 1, 4, 1, 5, 9, 0, 0, 0, 0];
+        remove_zeros(&mut v);
+        assert_eq!(vec![3, 1, 4, 1, 5, 9], v,);
+
+        let mut v = vec![0, 0, 0];
+        remove_zeros(&mut v);
+        assert_eq!(Vec::<usize>::new(), v);
+
+        let mut v = vec![8];
+        remove_zeros(&mut v);
+        assert_eq!(vec![8], v);
+
+        let mut v = vec![];
+        remove_zeros(&mut v);
+        assert_eq!(Vec::<usize>::new(), v);
+
+        let mut v = vec![0];
+        remove_zeros(&mut v);
+        assert_eq!(Vec::<usize>::new(), v);
+
+        let mut v = vec![1, 0, 0, 0];
+        remove_zeros(&mut v);
+        assert_eq!(vec![1], v);
+    }
+}