[1900][3A] CF1697D 交互 二分

Author: EndlessCheng

main/1600-1699/1697D.go

@@ -0,0 +1,108 @@
+package main
+
+import (
+	"bufio"
+	. "fmt"
+	"os"
+	"sort"
+	"strconv"
+)
+
+// https://space.bilibili.com/206214
+type interaction97 interface {
+	readInitData() initData97
+	query(request97) response97
+	printAnswer(answer97)
+}
+
+type stdIO97 struct {
+	in  *bufio.Reader
+	out *bufio.Writer
+}
+
+type (
+	initData97 struct{ n int }
+	request97  struct{ q []int }
+	response97 struct{ res string }
+	answer97   struct{ ans string }
+)
+
+func (io stdIO97) readInitData() initData97 {
+	in := io.in
+
+	var n int
+	Fscan(in, &n)
+
+	return initData97{n}
+}
+
+func (io stdIO97) query(q request97) (resp response97) {
+	in, out := io.in, io.out
+
+	Fprint(out, "?")
+	for _, v := range q.q {
+		Fprint(out, " ", v)
+	}
+	Fprintln(out)
+
+	out.Flush()
+
+	Fscan(in, &resp.res)
+
+	if resp.res == "0" {
+		panic(-1)
+	}
+	return
+}
+
+func (io stdIO97) printAnswer(a answer97) {
+	out := io.out
+
+	Fprintln(out, "!", a.ans)
+
+	out.Flush()
+}
+
+func doInteraction97(it interaction97) {
+	dt := it.readInitData()
+	n := dt.n
+
+	getChar := func(i int) byte {
+		return it.query(request97{[]int{1, i + 1}}).res[0]
+	}
+	getDiff := func(l, r int) int {
+		v, _ := strconv.Atoi(it.query(request97{[]int{2, l + 1, r + 1}}).res)
+		return v
+	}
+
+	ans := make([]byte, n)
+	defer func() { it.printAnswer(answer97{string(ans)}) }()
+
+	type pair struct {
+		i int
+		b byte
+	}
+	pos := []pair{}
+	for i := n - 1; i >= 0; i-- {
+		j := sort.Search(len(pos), func(j int) bool { return getDiff(i, pos[j].i) == j+1 })
+		if j < len(pos) {
+			ans[i] = pos[j].b
+			pos = append(pos[:j], pos[j+1:]...)
+		} else {
+			ans[i] = getChar(i)
+		}
+		pos = append([]pair{{i, ans[i]}}, pos...)
+	}
+}
+
+func run97() {
+	in := bufio.NewReader(os.Stdin)
+	out := bufio.NewWriter(os.Stdout)
+
+	T := 1
+	for ; T > 0; T-- {
+		doInteraction97(stdIO97{in, out})
+	}
+}
+
+//func main() { run97() }