codeforce R 491 (div2)
阿新 • • 發佈：2018-06-24
asn cep 二分 exception else if 發現 tar stream ans
本來打完就想寫的，，奈何舍友要睡了，我開個臺燈感覺怪怪的，就沒寫。
A題竟然一開始wa了。。。後來發現對於c和a還有c和b的關系沒有判斷，，丟掉了很多罰時。
B題我的方法是 計算 sum，然後 分別統計 2、3、4的個數，一個一個試，具體看代碼(前面快速io有點長見諒
package R491;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.StringTokenizer;
public class Main2 {
static BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
static StringTokenizer tok;
static boolean hasNext()
{
while(tok==null||!tok.hasMoreTokens())
try{
tok=new StringTokenizer(in.readLine());
}
catch(Exception e){
return false;
}
return true;
}
static String next()
{
hasNext();
return tok.nextToken();
}
static long nextLong()
{
return Long.parseLong(next());
}
static int nextInt()
{
return Integer.parseInt(next());
}
static PrintWriter out=new PrintWriter(new OutputStreamWriter(System.out));
public static void main(String[] args) {
int n = nextInt();
int a[] = new int[n];
int b[] = new int[8];
int sum = 0;
for(int i=0;i<n;i++){
a[i] = nextInt();
b[a[i]]++;
sum+=a[i];
}
int num = 0;
while (sum<4.5*n){
if (b[2]>0){
sum+=3;
b[2]--;
num++;
}else if (b[3]>0){
sum+=2;
b[3]--;
num++;
}else if (b[4]>0){
sum+=1;
b[4]--;
num++;
}
}
out.print(num);
out.flush();
}
}
C 一開始還以為可能有點意思，然後二分板子就出來了，沒啥可說的，中間竟然wa了一發，，很玄學， ，判斷時 如果 把 num1>=num2 寫成 num1>=(double)n/2 就會wa。。。
package R491;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.StringTokenizer;
public class Main3 {
static BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
static StringTokenizer tok;
static boolean hasNext()
{
while(tok==null||!tok.hasMoreTokens())
try{
tok=new StringTokenizer(in.readLine());
}
catch(Exception e){
return false;
}
return true;
}
static String next()
{
hasNext();
return tok.nextToken();
}
static long nextLong()
{
return Long.parseLong(next());
}
static int nextInt()
{
return Integer.parseInt(next());
}
static PrintWriter out=new PrintWriter(new OutputStreamWriter(System.out));
static long n;
public static void main(String[] args) {
n = nextLong();
long l = 1;
long r = n;
while (l<=r){
long mid=(l+r)/2;
if (caneat(mid)){
r=mid-1;
}else {
l=mid+1;
}
}
out.print(l);
out.flush();
}
public static boolean caneat(long k){
long num=0;
long num2 = 0;
long temp = n;
while (temp>0){
if (temp<k){
num+=temp;
break;
}
num+=k;
temp-=k;
num2+=(temp/10);
temp-=temp/10;
}
if (num>=num2){
return true;
}else {
return false;
}
}
}
D題就很和藹可親了，竟然只有兩行，直接暴力，我的方法是 umm懶得說看代碼吧
package R491;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.StringTokenizer;
public class Main4 {
static BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
static StringTokenizer tok;
static boolean hasNext()
{
while(tok==null||!tok.hasMoreTokens())
try{
tok=new StringTokenizer(in.readLine());
}
catch(Exception e){
return false;
}
return true;
}
static String next()
{
hasNext();
return tok.nextToken();
}
static long nextLong()
{
return Long.parseLong(next());
}
static int nextInt()
{
return Integer.parseInt(next());
}
static PrintWriter out=new PrintWriter(new OutputStreamWriter(System.out));
public static void main(String[] args) {
String s[] = new String[2];
for(int i=0;i<2;i++){
s[i] = next();
}
if (s[0].length()==1){
out.print(0);
out.flush();
return;
}
char ch1[] = s[0].toCharArray();
char ch2[] = s[1].toCharArray();
int ans = 0;
for(int i=0;i<ch1.length;i++){
if (ch1[i]==‘0‘&&ch2[i]==‘0‘){
if (i==0){
if (ch1[i+1]==‘0‘){
ans++;
ch1[i+1]=‘X‘;
ch1[i]=ch2[i]=‘X‘;
}else if (ch2[i+1]==‘0‘){
ans++;
ch2[i+1]=‘X‘;
ch1[i]=ch2[i]=‘X‘;
}
}else if (i<ch1.length-1){
if (ch1[i-1]==‘0‘){
ans++;
ch1[i-1]=‘X‘;
ch1[i]=ch2[i]=‘X‘;
}else if (ch2[i-1]==‘0‘){
ans++;
ch2[i-1]=‘X‘;
ch1[i]=ch2[i]=‘X‘;
}else if (ch1[i+1]==‘0‘){
ans++;
ch1[i+1]=‘X‘;
ch1[i]=ch2[i]=‘X‘;
}else if (ch2[i+1]==‘0‘){
ans++;
ch2[i+1]=‘X‘;
ch1[i]=ch2[i]=‘X‘;
}
}else if (i== ch1.length-1) {
if (ch1[i - 1] == ‘0‘) {
ans++;
ch1[i - 1] = ‘X‘;
ch1[i] = ch2[i] = ‘X‘;
} else if (ch2[i - 1] == ‘0‘) {
ans++;
ch2[i - 1] = ‘X‘;
ch1[i] = ch2[i] = ‘X‘;
}
}
}
}
out.print(ans);
out.flush();
}
}
E 啊哈哈哈哈，尷尬而不失禮貌的微笑，因為我太弱了又很垃圾還是一個數學白癡所以我沒寫出來。。。
F學長都沒寫。。。學長51分鐘過掉ABCDE好像就開始掛機了，發現F有點難就睡覺去了，然後D題掉了，囍。
近期：補一下排列組合，抓緊學個tarjan把前天的E題補掉。(對不起是我太弱了不會tarjan
rating:1548
忽然發現今晚還有一場，我可能要1600+了欸嘿嘿嘿。
codeforce R 491 (div2)