[2300] CF888G

main/800-899/888G.go

@@ -0,0 +1,79 @@
+package main
+
+import (
+	"bufio"
+	. "fmt"
+	"io"
+	"math"
+)
+
+// https://space.bilibili.com/206214
+type trieNode struct{ son [2]*trieNode }
+
+type trie struct{ root *trieNode }
+
+const trieBitLen = 30
+
+func (t *trie) put(v int32) *trieNode {
+	o := t.root
+	for i := trieBitLen - 1; i >= 0; i-- {
+		b := v >> i & 1
+		if o.son[b] == nil {
+			o.son[b] = &trieNode{}
+		}
+		o = o.son[b]
+	}
+	return o
+}
+
+func (t *trie) minXor(v int32) (ans int) {
+	o := t.root
+	for i := trieBitLen - 1; i >= 0; i-- {
+		b := v >> i & 1
+		if o.son[b] == nil {
+			ans |= 1 << i
+			b ^= 1
+		}
+		o = o.son[b]
+	}
+	return
+}
+
+func CF888G(_r io.Reader, out io.Writer) {
+	in := bufio.NewReader(_r)
+	var n, ans int
+	Fscan(in, &n)
+	a := make([]int32, n)
+	for i := range a {
+		Fscan(in, &a[i])
+	}
+
+	var f func([]int32, int)
+	f = func(a []int32, p int) {
+		if a == nil || p < 0 {
+			return
+		}
+		b := [2][]int32{}
+		for _, v := range a {
+			k := v >> p & 1
+			b[k] = append(b[k], v)
+		}
+		if b[0] != nil && b[1] != nil {
+			t := &trie{&trieNode{}}
+			for _, v := range b[0] {
+				t.put(v)
+			}
+			res := math.MaxInt
+			for _, v := range b[1] {
+				res = min(res, t.minXor(v))
+			}
+			ans += res
+		}
+		f(b[0], p-1)
+		f(b[1], p-1)
+	}
+	f(a, 29)
+	Fprint(out, ans)
+}
+
+//func main() { CF888G(os.Stdin, os.Stdout) }