[1800] CF1225D 质因子分解+哈希

Author: EndlessCheng

main/1200-1299/1225D.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"bufio"
+	. "fmt"
+	"io"
+)
+
+// github.com/EndlessCheng/codeforces-go
+func CF1225D(_r io.Reader, out io.Writer) {
+	in := bufio.NewReader(_r)
+	const mx int = 1e5
+	lpf := [mx + 1]int{1: 1}
+	for i := 2; i <= mx; i++ {
+		if lpf[i] == 0 {
+			for j := i; j <= mx; j += i {
+				if lpf[j] == 0 {
+					lpf[j] = i
+				}
+			}
+		}
+	}
+
+	var n, k, v int
+	ans := int64(0)
+	cnt := map[string]int{} // 或者用 [6]int 来代替 string，下面改成 p<<8|e 和 p<<8|(k-e)
+	for Fscan(in, &n, &k); n > 0; n-- {
+		s := []byte{}
+		t := []byte{}
+		Fscan(in, &v)
+		for v > 1 {
+			p, e := lpf[v], 1
+			for v /= p; lpf[v] == p; v /= p {
+				e++
+			}
+			if e %= k; e > 0 {
+				s = append(s, byte(p>>16), byte(p>>8), byte(p), byte(e))
+				t = append(t, byte(p>>16), byte(p>>8), byte(p), byte(k-e))
+			}
+		}
+		ans += int64(cnt[string(t)])
+		cnt[string(s)]++
+	}
+	Fprint(out, ans)
+}
+
+//func main() { CF1225D(os.Stdin, os.Stdout) }

main/1200-1299/1225D_test.go

@@ -0,0 +1,19 @@
+package main
+
+import (
+	"github.com/EndlessCheng/codeforces-go/main/testutil"
+	"testing"
+)
+
+// https://codeforces.com/problemset/problem/1225/D
+// https://codeforces.com/problemset/status/1225/problem/D
+func TestCF1225D(t *testing.T) {
+	// just copy from website
+	rawText := `
+inputCopy
+6 3
+1 3 9 8 24 1
+outputCopy
+5`
+	testutil.AssertEqualCase(t, rawText, 1, CF1225D)
+}