Initial data commit

Task/Eertree/Go/eertree.go

@@ -0,0 +1,74 @@
+package main
+
+import "fmt"
+
+func main() {
+    tree := eertree([]byte("eertree"))
+    fmt.Println(subPalindromes(tree))
+}
+
+type edges map[byte]int
+
+type node struct {
+    length int
+    edges
+    suffix int
+}
+
+const evenRoot = 0
+const oddRoot = 1
+
+func eertree(s []byte) []node {
+    tree := []node{
+        evenRoot: {length: 0, suffix: oddRoot, edges: edges{}},
+        oddRoot:  {length: -1, suffix: oddRoot, edges: edges{}},
+    }
+    suffix := oddRoot
+    var n, k int
+    for i, c := range s {
+        for n = suffix; ; n = tree[n].suffix {
+            k = tree[n].length
+            if b := i - k - 1; b >= 0 && s[b] == c {
+                break
+            }
+        }
+        if e, ok := tree[n].edges[c]; ok {
+            suffix = e
+            continue
+        }
+        suffix = len(tree)
+        tree = append(tree, node{length: k + 2, edges: edges{}})
+        tree[n].edges[c] = suffix
+        if tree[suffix].length == 1 {
+            tree[suffix].suffix = 0
+            continue
+        }
+        for {
+            n = tree[n].suffix
+            if b := i - tree[n].length - 1; b >= 0 && s[b] == c {
+                break
+            }
+        }
+        tree[suffix].suffix = tree[n].edges[c]
+    }
+    return tree
+}
+
+func subPalindromes(tree []node) (s []string) {
+    var children func(int, string)
+    children = func(n int, p string) {
+        for c, n := range tree[n].edges {
+            c := string(c)
+            p := c + p + c
+            s = append(s, p)
+            children(n, p)
+        }
+    }
+    children(0, "")
+    for c, n := range tree[1].edges {
+        c := string(c)
+        s = append(s, c)
+        children(n, c)
+    }
+    return
+}