tasks a-s

Task/Run-length-encoding/D/run-length-encoding-4.d

@@ -0,0 +1,32 @@
+import std.stdio, std.conv, std.array, std.regex, std.utf,
+       std.algorithm;
+
+string reEncode(string s) {
+    validate(s); // Throw if it's not a well-formed UTF string
+    static string rep(Captures!string m) {
+        auto c = canFind("0123456789#", m[1]) ? "#" ~ m[1] : m[1];
+        return text(m.hit.length / m[1].length) ~ c;
+    }
+    return std.regex.replace!rep(s, regex(`(.|[\n\r\f])\1*`, "g"));
+}
+
+
+string reDecode(string s) {
+    validate(s); // Throw if it's not a well-formed UTF string
+    static string rep(Captures!string m) {
+        string c = m[2];
+        if (c.length > 1 && c[0] == '#')
+            c = c[1 .. $];
+        return replicate(c, to!int(m[1]));
+    }
+    auto r=regex(`(\d+)(#[0123456789#]|[\n\r\f]|[^0123456789#\n\r\f]+)`
+                 , "g");
+    return std.regex.replace!rep(s, r);
+}
+
+void main() {
+    auto s = "尋尋覓覓冷冷清清淒淒慘慘戚戚\nWWWWWWWWWWWWBWWWWWWWWWWW" ~
+             "WBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW\n" ~
+             "11#222##333";
+    assert(s == reDecode(reEncode(s)));
+}