[2300] CF327E 状压 DP

Author: EndlessCheng

main/300-399/327E.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	. "fmt"
+	"io"
+)
+
+// 另一种效率更高的做法是折半枚举，见 https://codeforces.com/blog/entry/8274
+
+// github.com/EndlessCheng/codeforces-go
+func CF327E(in io.Reader, out io.Writer) {
+	const mod int = 1e9 + 7
+	var n, k int
+	Fscan(in, &n)
+	m := 1 << n
+	sum := make([]int, m)
+	for i := 0; i < n; i++ {
+		Fscan(in, &sum[1<<i])
+	}
+	b := [2]int{}
+	Fscan(in, &k, &b[0], &b[1])
+	f := make([]int, m)
+	f[0] = 1
+	for s := 1; s < m; s++ {
+		lb := s & -s
+		v := sum[s^lb] + sum[lb]
+		if v > 1e9+1 {
+			v = 1e9 + 1
+		}
+		sum[s] = v
+		if v != b[0] && v != b[1] {
+			dv := 0
+			for sub, lb := s, 0; sub > 0; sub ^= lb {
+				lb = sub & -sub
+				dv += f[s^lb]
+				if dv >= mod {
+					dv -= mod
+				}
+			}
+			f[s] = dv
+		}
+	}
+	Fprint(out, f[1<<n-1])
+}
+
+//func main() { CF327E(os.Stdin, os.Stdout) }

main/300-399/327E_test.go

@@ -0,0 +1,28 @@
+package main
+
+import (
+	"github.com/EndlessCheng/codeforces-go/main/testutil"
+	"testing"
+)
+
+// https://codeforces.com/problemset/problem/327/E
+// https://codeforces.com/problemset/status/327/problem/E
+func TestCF327E(t *testing.T) {
+	// just copy from website
+	rawText := `
+inputCopy
+3
+2 3 5
+2
+5 7
+outputCopy
+1
+inputCopy
+3
+2 2 2
+2
+1 3
+outputCopy
+6`
+	testutil.AssertEqualCase(t, rawText, 0, CF327E)
+}