cf660F

Author: EndlessCheng

main/600-699/660F.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	. "fmt"
+	"io"
+	"math/big"
+	"sort"
+)
+
+// https://github.com/EndlessCheng
+type vec60 struct{ x, y int }
+func (a vec60) sub(b vec60) vec60 { return vec60{a.x - b.x, a.y - b.y} }
+func (a vec60) dot(b vec60) int   { return a.x*b.x + a.y*b.y }
+func (a vec60) detCmp(b vec60) int {
+	v := new(big.Int).Mul(big.NewInt(int64(a.x)), big.NewInt(int64(b.y)))
+	w := new(big.Int).Mul(big.NewInt(int64(a.y)), big.NewInt(int64(b.x)))
+	return v.Cmp(w)
+}
+
+func cf660F(in io.Reader, out io.Writer) {
+	var n, v, s, s2, ans int
+	Fscan(in, &n)
+	q := []vec60{{}}
+	for i := 1; i <= n; i++ {
+		Fscan(in, &v)
+		s += v
+		s2 += v * i
+
+		p := vec60{-s, 1}
+		j := sort.Search(len(q)-1, func(j int) bool { return p.dot(q[j]) > p.dot(q[j+1]) })
+		ans = max(ans, p.dot(q[j])+s2)
+
+		p = vec60{i, s*i - s2}
+		for len(q) > 1 && q[len(q)-1].sub(q[len(q)-2]).detCmp(p.sub(q[len(q)-1])) >= 0 {
+			q = q[:len(q)-1]
+		}
+		q = append(q, p)
+	}
+	Fprint(out, ans)
+}
+
+//func main() { cf660F(bufio.NewReader(os.Stdin), os.Stdout) }

main/600-699/660F_test.go

@@ -0,0 +1,30 @@
+// Generated by copypasta/template/generator_test.go
+package main
+
+import (
+	"github.com/EndlessCheng/codeforces-go/main/testutil"
+	"testing"
+)
+
+// https://codeforces.com/problemset/problem/660/F
+// https://codeforces.com/problemset/status/660/problem/F?friends=on
+func Test_cf660F(t *testing.T) {
+	testCases := [][2]string{
+		{
+			`6
+5 -1000 1 -3 7 -8`,
+			`16`,
+		},
+		{
+			`5
+1000 1000 1001 1000 1000`,
+			`15003`,
+		},
+		{
+			`3
+-60 -70 -80`,
+			`0`,
+		},
+	}
+	testutil.AssertEqualStringCase(t, testCases, 0, cf660F)
+}