CDE

Task/Balanced-brackets/D/balanced-brackets-1.d

@@ -0,0 +1,10 @@
+import std.stdio, std.algorithm, std.random;
+
+void main() {
+    foreach (i; 1 .. 9) {
+        string s;
+        foreach (_; 0 .. i * 2)
+            s ~= "[]"[uniform(0, 2)];
+        writeln(s.balancedParens('[', ']') ? " OK: " : "bad: ", s);
+    }
+}

Task/Balanced-brackets/D/balanced-brackets-2.d

@@ -0,0 +1,20 @@
+import std.stdio, std.random;
+
+void main() {
+NEXT_STR:
+    foreach (j; 1 .. 9) {
+        string s;
+        foreach (_; 0 .. j * 2)
+            s ~= "[]"[uniform(0, 2)];
+
+        int balance;
+        foreach (i, c; s) {
+            balance += (c == '[') ? 1 : ((c == ']') ? -1 : 0);
+            if (balance < 0 || balance >= s.length - i) {
+                writefln("BAD: %s (%s)", s, balance < 0 ? "-" : "+");
+                continue NEXT_STR;
+            }
+        }
+        writefln(" OK: %s (=)", s);
+    }
+}

Task/Balanced-brackets/D/balanced-brackets-3.d

@@ -0,0 +1,20 @@
+import std.stdio, std.random, std.conv, std.range, std.algorithm;
+
+bool isBalanced(in char[] s) pure nothrow {
+    static bool bal(in char[] s, in int nb=0) pure nothrow {
+        if (nb == 0 && s.empty) return true;
+        if (s.empty || nb < 0) return false;
+        if (s[0] == '[') return bal(s[1 .. $], nb + 1);
+        if (s[0] == ']') return bal(s[1 .. $], nb - 1);
+        return bal(s[1 .. $], nb); // ignore char
+    }
+    return bal(s);
+}
+
+void main() {
+    foreach (i; 1 .. 9) {
+        auto sr = iota(i * 2).map!(_ => ['[',']'][uniform(0, 2)])();
+        auto s = sr.array();
+        writefln("%5s: %s", s.isBalanced().text(), s);
+    }
+}