[1800] CF1450D 观察 结论题

Author: EndlessCheng

main/1400-1499/1450D.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"bufio"
+	"bytes"
+	. "fmt"
+	"io"
+)
+
+// github.com/EndlessCheng/codeforces-go
+func CF1450D(_r io.Reader, _w io.Writer) {
+	in := bufio.NewReader(_r)
+	out := bufio.NewWriter(_w)
+	defer out.Flush()
+
+	var T, n int
+	for Fscan(in, &T); T > 0; T-- {
+		Fscan(in, &n)
+		a := make([]int, n)
+		c := make([]int, n)
+		ans := bytes.Repeat([]byte{'0'}, n)
+		ans[0] = '1'
+		for i := range a {
+			Fscan(in, &a[i])
+			a[i]--
+			c[a[i]]++
+			if c[a[i]] > 1 {
+				ans[0] = '0'
+			}
+		}
+		l, r := 0, n-1
+		for i, c := range c {
+			if c == 0 {
+				break
+			}
+			ans[n-1-i] = '1'
+			if c > 1 || a[l] != i && a[r] != i {
+				break
+			}
+			if a[l] == i {
+				l++
+			} else {
+				r--
+			}
+		}
+		Fprintf(out, "%s\n", ans)
+	}
+}
+
+//func main() { CF1450D(os.Stdin, os.Stdout) }

main/1400-1499/1450D_test.go

@@ -0,0 +1,32 @@
+package main
+
+import (
+	"github.com/EndlessCheng/codeforces-go/main/testutil"
+	"testing"
+)
+
+// https://codeforces.com/problemset/problem/1450/D
+// https://codeforces.com/problemset/status/1450/problem/D
+func TestCF1450D(t *testing.T) {
+	// just copy from website
+	rawText := `
+inputCopy
+5
+5
+1 5 3 4 2
+4
+1 3 2 1
+5
+1 3 3 3 2
+10
+1 2 3 4 5 6 7 8 9 10
+3
+3 3 2
+outputCopy
+10111
+0001
+00111
+1111111111
+000`
+	testutil.AssertEqualCase(t, rawText, 0, CF1450D)
+}