Init: w9 code done

intset.go

@@ -0,0 +1,116 @@
+package intset
+
+import (
+	"bytes"
+	"fmt"
+	"math/bits"
+	"slices"
+)
+
+type IntSet struct {
+	words []uint64
+}
+
+func (s *IntSet) Has(x int) bool {
+	word, bit := x/64, uint(x%64)
+	return word < len(s.words) && s.words[word]&uint64(1<<bit) != 0
+}
+
+func (s *IntSet) Add(x int) {
+	word, bit := x/64, uint(x%64)
+	for word >= len(s.words) {
+		s.words = append(s.words, 0)
+	}
+	s.words[word] |= uint64(1 << bit)
+}
+
+func (s *IntSet) UnionWith(t *IntSet) {
+	for i, tword := range t.words {
+		if i < len(s.words) {
+			s.words[i] |= tword
+		} else {
+			s.words = append(s.words, tword)
+		}
+	}
+}
+
+func (s *IntSet) String() string {
+	var buf bytes.Buffer
+	buf.WriteByte('{')
+	for i, word := range s.words {
+		if word == 0 {
+			continue
+		}
+		for j := 0; j < 64; j++ {
+			if word&uint64(1<<uint(j)) != 0 {
+				if buf.Len() > len("{") {
+					buf.WriteByte(' ')
+				}
+				fmt.Fprintf(&buf, "%d", 64*i+j)
+			}
+		}
+	}
+	buf.WriteByte('}')
+	return buf.String()
+}
+
+func (s *IntSet) Len() int {
+	res := 0
+	for _, word := range s.words {
+		res += bits.OnesCount64(word)
+	}
+	return res
+}
+
+func (s *IntSet) Remove(x int) {
+	word, bit := x/64, uint(x%64)
+	if word < len(s.words) {
+		s.words[word] &= ^(1 << bit)
+	}
+}
+
+func (s *IntSet) Clear() {
+	s.words = []uint64{}
+}
+
+func (s *IntSet) Copy() *IntSet {
+	return &IntSet{
+		words: slices.Clone(s.words),
+	}
+}
+
+func (s *IntSet) AddAll(xs ...int) {
+	for _, x := range xs {
+		s.Add(x)
+	}
+}
+
+func (s *IntSet) IntersectWith(o *IntSet) {
+	for word := range s.words {
+		if word >= len(o.words) {
+			return
+		}
+		s.words[word] &= o.words[word]
+	}
+}
+
+func (s *IntSet) DifferenceWith(o *IntSet) {
+	for word := range s.words {
+		if word >= len(o.words) {
+			return
+		}
+		s.words[word] &= ^o.words[word]
+	}
+}
+
+func (s *IntSet) SymmetricDifference(o *IntSet) {
+	for word := range s.words {
+		if word >= len(o.words) {
+			return
+		}
+		s.words[word] ^= o.words[word]
+	}
+	for i := len(s.words); i < len(o.words); i++ {
+		s.words = append(s.words, o.words[i])
+	}
+}