Data commit

Task/Eertree/D/eertree.d

@@ -0,0 +1,72 @@
+import std.array;
+import std.stdio;
+
+void main() {
+    auto tree = eertree("eertree");
+    writeln(subPalindromes(tree));
+}
+
+struct Node {
+    int length;
+    int[char] edges;
+    int suffix;
+}
+
+const evenRoot = 0;
+const oddRoot = 1;
+
+Node[] eertree(string s) {
+    Node[] tree = [
+        Node(0, null, oddRoot),
+        Node(-1, null, oddRoot),
+    ];
+    int suffix = oddRoot;
+    int n, k;
+    foreach (i, c; s) {
+        for (n=suffix; ; n=tree[n].suffix) {
+            k = tree[n].length;
+            int b = i-k-1;
+            if (b>=0 && s[b]==c) {
+                break;
+            }
+        }
+        if (c in tree[n].edges) {
+            suffix = tree[n].edges[c];
+            continue;
+        }
+        suffix = tree.length;
+        tree ~= Node(k+2);
+        tree[n].edges[c] = suffix;
+        if (tree[suffix].length == 1) {
+            tree[suffix].suffix = 0;
+            continue;
+        }
+        while (true) {
+            n = tree[n].suffix;
+            int b = i-tree[n].length-1;
+            if (b>=0 && s[b]==c) {
+                break;
+            }
+        }
+        tree[suffix].suffix = tree[n].edges[c];
+    }
+    return tree;
+}
+
+auto subPalindromes(Node[] tree) {
+    auto s = appender!(string[]);
+    void children(int n, string p) {
+        foreach (c, n; tree[n].edges) {
+            p = c ~ p ~ c;
+            s ~= p;
+            children(n, p);
+        }
+    }
+    children(0, "");
+    foreach (c, n; tree[1].edges) {
+        string ct = [c].idup;
+        s ~= ct;
+        children(n, ct);
+    }
+    return s.data;
+}