Data update

Task/Move-to-front-algorithm/EasyLang/move-to-front-algorithm.easy

@@ -1,7 +1,7 @@
 subr init
    symt$[] = strchars "abcdefghijklmnopqrstuvwxyz"
 .
-proc rot k . .
+proc rot k .
    c$ = symt$[k]
    for j = k downto 2
       symt$[j] = symt$[j - 1]

Task/Move-to-front-algorithm/Zig/move-to-front-algorithm.zig

@@ -0,0 +1,78 @@
+const std = @import("std");
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    const allocator = gpa.allocator();
+    defer _ = gpa.deinit();
+
+    const examples = [_][]const u8{ "broood", "bananaaa", "hiphophiphop" };
+
+    for (examples) |example| {
+        const encoded = try encode(allocator, example);
+        defer allocator.free(encoded);
+
+        const decoded = try decode(allocator, encoded);
+        defer allocator.free(decoded);
+
+        std.debug.print("{s} encodes to {any} decodes to {s}\n", .{ example, encoded, decoded });
+    }
+}
+
+fn getSymbols(allocator: std.mem.Allocator) ![]u8 {
+    var symbols = std.ArrayList(u8).init(allocator);
+    errdefer symbols.deinit();
+
+    var c: u8 = 'a';
+    while (c <= 'z') : (c += 1) {
+        try symbols.append(c);
+    }
+
+    return symbols.toOwnedSlice();
+}
+
+fn encode(allocator: std.mem.Allocator, input: []const u8) ![]usize {
+    var output = std.ArrayList(usize).init(allocator);
+    errdefer output.deinit();
+
+    var symbols = try getSymbols(allocator);
+    defer allocator.free(symbols);
+
+    for (input) |byte| {
+        // Find position of the byte in symbols
+        var position: usize = 0;
+        for (symbols, 0..) |symbol, i| {
+            if (symbol == byte) {
+                position = i;
+                break;
+            }
+        }
+
+        // Remove the byte at the position
+        const char = symbols[position];
+        std.mem.copyForwards(u8, symbols[1..position + 1], symbols[0..position]);
+        symbols[0] = char;
+
+        try output.append(position);
+    }
+
+    return output.toOwnedSlice();
+}
+
+fn decode(allocator: std.mem.Allocator, input: []const usize) ![]u8 {
+    var output = std.ArrayList(u8).init(allocator);
+    errdefer output.deinit();
+
+    var symbols = try getSymbols(allocator);
+    defer allocator.free(symbols);
+
+    for (input) |position| {
+        try output.append(symbols[position]);
+
+        // Remove the byte at the position
+        const char = symbols[position];
+        std.mem.copyForwards(u8, symbols[1..position + 1], symbols[0..position]);
+        symbols[0] = char;
+    }
+
+    return output.toOwnedSlice();
+}