Data commit

Task/Entropy/Zig/entropy.zig

@@ -0,0 +1,22 @@
+const std = @import("std");
+const math = std.math;
+
+pub fn main() !void {
+    const stdout = std.io.getStdOut().outStream();
+    try stdout.print("{d:.12}\n", .{H("1223334444")});
+}
+
+fn H(s: []const u8) f64 {
+    var counts = [_]u16{0} ** 256;
+    for (s) |ch|
+        counts[ch] += 1;
+
+    var h: f64 = 0;
+    for (counts) |c|
+        if (c != 0) {
+            const p = @intToFloat(f64, c) / @intToFloat(f64, s.len);
+            h -= p * math.log2(p);
+        };
+
+    return h;
+}