June 2018 Update

Task/Count-the-coins/Perl-6/count-the-coins.pl6

@@ -0,0 +1,30 @@
+# Recursive (cached)
+sub change-r($amount, @coins) {
+    my @cache = $[1 xx @coins];
+
+    multi ways($n where $n >= 0, @now [$coin,*@later]) {
+        @cache[$n][+@later] //= ways($n - $coin, @now) + ways($n, @later);
+    }
+    multi ways($,@) { 0 }
+
+    # more efficient to start with coins sorted in descending order
+    ways($amount, @coins.sort(-*).list);
+}
+
+change-r    1_00, [1,5,10,25];
+change-r 1000_00, [1,5,10,25,50,100];
+
+# Iterative
+sub change-i(\n, @coins) {
+    my @table = [1 xx @coins], [0 xx @coins] xx n;
+    for 1..n X ^@coins -> (\i, \j) {
+        my \c = @coins[j];
+        @table[i][j] = [+]
+            @table[i - c][j    ] // 0,
+            @table[i    ][j - 1] // 0;
+    }
+    @table[*-1][*-1];
+}
+
+say change-i    1_00, [1,5,10,25];
+say change-i 1000_00, [1,5,10,25,50,100];

Task/Count-the-coins/Rust/count-the-coins.rust

@@ -12,5 +12,5 @@ fn make_change(coins: &[usize], cents: usize) -> usize {
 
 fn main() {
     println!("{}", make_change(&[1,5,10,25], 100));
-    println!("{}", make_change(&[1,5,10,25,50,100], 100000));
+    println!("{}", make_change(&[1,5,10,25,50,100], 100_000));
 }