AtCoder Beginner Contest 170 参戦記
ABC170A - Five Variables
2分で突破. 書くだけ. 最初から xi が0の場合はどうすれば良いんだと思ったが、xi = i だった、あはは.
x = list(map(int, input().split()))
for i in range(5):
if x[i] == 0:
print(i + 1)
break
ABC170B - Crane and Turtle
2分半で突破. 書くだけ. O(1) で書けない辺りが弱い.
X, Y = map(int, input().split())
for i in range(X + 1):
if i * 2 + (X - i) * 4 == Y:
print('Yes')
break
else:
print('No')
ABC170C - Forbidden List
3分で突破. 差の絶対値が同じものが2つあった時に小さい方が優先されることだけ気にして書くだけ. 解説 PDF の「本問が問題Bとして出題されていたなら以下に具体的な実装方法を述べるところですが、問題Cを解かれる方にそのような説明は不要と考え、省略します。」にはウケた.
X, N = map(int, input().split())
p = list(map(int, input().split()))
p = set(p)
for i in range(200):
if X - i not in p:
print(X - i)
break
if X + i not in p:
print(X + i)
break
ABC170D - Not Divisible
56分半で突破. RE1、WA3. エラトステネスの篩っぽくやれば計算量が下がるんだって気づくまでが長かった.
N = int(input())
A = list(map(int, input().split()))
d = {}
for a in A:
d.setdefault(a, 0)
d[a] += 1
A = sorted(set(A))
t = [True] * (10 ** 6 + 1)
for a in A:
if d[a] > 1:
t[a] = False
for i in range(a + a, 10 ** 6 + 1, a):
t[i] = False
print(sum(1 for a in A if t[a]))
ABC170E - Smart Infants
突破できず. multiset だよなあと思ったけど、Python にはビルトインで multiset ないし、残り時間も足りなかった……. 自前の Treap をもうちょっと汎用性があるように書き直しておくべきか…….
追記: Python で書いたら TLE になったので、仕方がなく C++ で書いた. まあ、multiset があれば特に難しいところはないよね…….
#include <bits/stdc++.h>
#define rep(i, a) for (int i = (int)0; i < (int)a; ++i)
using namespace std;
int main()
{
int N, Q;
cin >> N >> Q;
multiset<int> max_ratings;
vector<multiset<int>> kindergartens(2 * pow(10, 5) + 1);
vector<int> ratings(N + 1), belongs(N + 1);
rep(i, N) {
int A, B;
cin >> A >> B;
ratings[i + 1] = A;
belongs[i + 1] = B;
kindergartens[B].insert(A);
}
rep(i, 2 * pow(10, 5) + 1) {
if (kindergartens[i].size() != 0) {
max_ratings.insert(*kindergartens[i].rbegin());
}
}
rep(_, Q) {
int C, D;
cin >> C >> D;
int b = belongs[C];
belongs[C] = D;
max_ratings.erase(max_ratings.find(*kindergartens[b].rbegin()));
kindergartens[b].erase(ratings[C]);
if (kindergartens[b].size() != 0) {
max_ratings.insert(*kindergartens[b].rbegin());
}
if (kindergartens[D].size() != 0) {
max_ratings.erase(max_ratings.find(*kindergartens[D].rbegin()));
}
kindergartens[D].insert(ratings[C]);
max_ratings.insert(*kindergartens[D].rbegin());
cout << *max_ratings.begin() << endl;
}
return 0;
}
go でも通した.
package main
import (
"bufio"
"fmt"
"os"
"strconv"
"strings"
)
var (
y uint = 88172645463325252
)
func xorshift() uint {
y ^= y << 7
y ^= y >> 9
return y
}
type treapNode struct {
value int
priority uint
count int
left *treapNode
right *treapNode
}
func newTreapNode(v int) *treapNode {
return &treapNode{v, xorshift(), 1, nil, nil}
}
func treapRotateRight(n *treapNode) *treapNode {
l := n.left
n.left = l.right
l.right = n
return l
}
func treapRotateLeft(n *treapNode) *treapNode {
r := n.right
n.right = r.left
r.left = n
return r
}
func treapInsert(n *treapNode, v int) *treapNode {
if n == nil {
return newTreapNode(v)
}
if n.value == v {
n.count++
return n
}
if n.value > v {
n.left = treapInsert(n.left, v)
if n.priority > n.left.priority {
n = treapRotateRight(n)
}
} else {
n.right = treapInsert(n.right, v)
if n.priority > n.right.priority {
n = treapRotateLeft(n)
}
}
return n
}
func treapDelete(n *treapNode, v int) *treapNode {
if n == nil {
panic("node is not found!")
}
if n.value > v {
n.left = treapDelete(n.left, v)
return n
}
if n.value < v {
n.right = treapDelete(n.right, v)
return n
}
// n.value == v
if n.count > 1 {
n.count--
return n
}
if n.left == nil && n.right == nil {
return nil
}
if n.left == nil {
n = treapRotateLeft(n)
} else if n.right == nil {
n = treapRotateRight(n)
} else {
// n.left != nil && n.right != nil
if n.left.priority < n.right.priority {
n = treapRotateRight(n)
} else {
n = treapRotateLeft(n)
}
}
return treapDelete(n, v)
}
func treapCount(n *treapNode) int {
if n == nil {
return 0
}
return n.count + treapCount(n.left) + treapCount(n.right)
}
func treapString(n *treapNode) string {
if n == nil {
return ""
}
result := make([]string, 0)
if n.left != nil {
result = append(result, treapString(n.left))
}
result = append(result, fmt.Sprintf("%d:%d", n.value, n.count))
if n.right != nil {
result = append(result, treapString(n.right))
}
return strings.Join(result, " ")
}
func treapMin(n *treapNode) int {
if n.left != nil {
return treapMin(n.left)
}
return n.value
}
func treapMax(n *treapNode) int {
if n.right != nil {
return treapMax(n.right)
}
return n.value
}
type treap struct {
root *treapNode
size int
}
func (t *treap) Insert(v int) {
t.root = treapInsert(t.root, v)
t.size++
}
func (t *treap) Delete(v int) {
t.root = treapDelete(t.root, v)
t.size--
}
func (t *treap) String() string {
return treapString(t.root)
}
func (t *treap) Count() int {
return t.size
}
func (t *treap) Min() int {
return treapMin(t.root)
}
func (t *treap) Max() int {
return treapMax(t.root)
}
func main() {
defer flush()
N := readInt()
Q := readInt()
maxRatings := &treap{}
kindergartens := make([]*treap, 200001)
for i := 0; i < 200001; i++ {
kindergartens[i] = &treap{}
}
ratings := make([]int, N+1)
belongs := make([]int, N+1)
for i := 1; i < N+1; i++ {
A := readInt()
B := readInt()
ratings[i] = A
belongs[i] = B
kindergartens[B].Insert(A)
}
for i := 1; i < 200001; i++ {
if kindergartens[i].Count() != 0 {
maxRatings.Insert(kindergartens[i].Max())
}
}
for i := 0; i < Q; i++ {
C := readInt()
D := readInt()
from := kindergartens[belongs[C]]
to := kindergartens[D]
rating := ratings[C]
belongs[C] = D
maxRatings.Delete(from.Max())
from.Delete(rating)
if from.Count() != 0 {
maxRatings.Insert(from.Max())
}
if to.Count() != 0 {
maxRatings.Delete(to.Max())
}
to.Insert(rating)
maxRatings.Insert(to.Max())
println(maxRatings.Min())
}
}
const (
ioBufferSize = 1 * 1024 * 1024 // 1 MB
)
var stdinScanner = func() *bufio.Scanner {
result := bufio.NewScanner(os.Stdin)
result.Buffer(make([]byte, ioBufferSize), ioBufferSize)
result.Split(bufio.ScanWords)
return result
}()
func readString() string {
stdinScanner.Scan()
return stdinScanner.Text()
}
func readInt() int {
result, err := strconv.Atoi(readString())
if err != nil {
panic(err)
}
return result
}
var stdoutWriter = bufio.NewWriter(os.Stdout)
func flush() {
stdoutWriter.Flush()
}
func println(args ...interface{}) (int, error) {
return fmt.Fprintln(stdoutWriter, args...)
}