/*
ID: chicc991
LANG: JAVA
TASK: milk2
*/
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.BitSet;
import java.util.Scanner;
public class milk2 {
public static void main(String[] args) throws Exception
{
Scanner sc =new Scanner(new FileReader(new File("data/milk2.in")));
PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("data/milk2.out")));
int n=sc.nextInt();
BitSet time=new BitSet(1000000);
for(int i=0;i<n;i++)
{
int start=sc.nextInt();
int end=sc.nextInt();
for(int j=start;j<end;j++)
time.set(j);
}
int maxtime=0;
int maxtime2=0;
int k=0;
int m=0;
for(int i=0;i<1000000;i++)
{
if(time.get(i))
{
k++;
if(m>maxtime2)
maxtime2=m;
m=0;
}else{
if(k>maxtime)
maxtime=k;
k=0;
if(maxtime!=0)
m++;
}
}
out.println(maxtime+" "+maxtime2);
out.close();
System.exit(0);
}
}
利用比特位，如果有奶农挤奶，则置为true
package chapter1_2;
/*
ID: chicc991
LANG: JAVA
TASK: transform
*/
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.Scanner;
public class transform {
private int[][] a;
private int[][] s;
private int N;
public static void main(String[] args) throws Exception {
transform main = new transform();
}
public transform() throws Exception {
Scanner sc = new Scanner(new FileReader(new File("data/transform.in")));
PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter(
"data/transform.out")));
while (sc.hasNext()) {
N = sc.nextInt();
a = new int[N][N];
s = new int[N][N];
for (int i = 0; i < N; i++) {
char[] c = sc.next().toCharArray();
for (int j = 0; j < N; j++) {
if (c[j] == '@')
a[i][j] = 0;
else
a[i][j] = 1;
}
}
for (int i = 0; i < N; i++) {
char[] c = sc.next().toCharArray();
for (int j = 0; j < N; j++) {
if (c[j] == '@')
s[i][j] = 0;
else
s[i][j] = 1;
}
}
out.println(transform(s, a));
}
sc.close();
out.close();
}
private int transform(int[][] a, int[][] b) {
if (isSame(a, rotate90(b)))
return 1;
else if (isSame(a, rotate180(b)))
return 2;
else if (isSame(a, rotate270(b)))
return 3;
else if (isSame(a, reflect(b)))
return 4;
else if (isSame(a, combination90(b)) || isSame(a, combination180(b))
|| isSame(a, combination270(b)))
return 5;
else if (isSame(a, b))
return 6;
else
return 7;
}
private boolean isSame(int[][] a, int[][] b) {
for (int i = 0; i < N; i++)
for (int j = 0; j < N; j++) {
if (a[i][j] != b[i][j])
return false;
}
return true;
}
private int[][] rotate90(int[][] a) {
int[][] b = new int[N][N];
for (int i = 0; i < N; i++)
for (int j = 0; j < N; j++) {
b[i][j] = a[N - 1 - j][i];
}
return b;
}
private int[][] rotate180(int[][] a) {
return rotate90(rotate90(a));
}
private int[][] rotate270(int[][] a) {
return rotate90(rotate90(rotate90(a)));
}
private int[][] reflect(int[][] a) {
int[][] b = new int[N][N];
for (int i = 0; i < N; i++)
for (int j = 0; j < N; j++) {
b[i][j] = a[i][N - 1 - j];
}
return b;
}
private int[][] combination90(int[][] a) {
return rotate90(reflect(a));
}
private int[][] combination180(int[][] a) {
return rotate180(reflect(a));
}
private int[][] combination270(int[][] a) {
return rotate270(reflect(a));
}
}
注意矩阵旋转90°的实现
namenum
package chapter1_2;
/*
ID: chicc991
LANG: JAVA
TASK: namenum
*/
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Scanner;
public class namenum
{
private HashSet<String> dict;
private HashMap<String, String> map;
private char[] c;
private StringBuilder sb;
private boolean flag;
private PrintWriter out;
public static void main(String[] args) throws Exception
{
namenum main = new namenum();
}
public namenum() throws Exception
{
init();
foo();
}
private void init() throws Exception
{
Scanner sc = new Scanner(new FileReader(new File("data/dict.txt")));
dict = new HashSet<String>();
while (sc.hasNext())
dict.add(sc.next());
map=new HashMap<String,String>();
map.put("2", "ABC");
map.put("3", "DEF");
map.put("4", "GHI");
map.put("5", "JKL");
map.put("6", "MNO");
map.put("7", "PRS");
map.put("8", "TUV");
map.put("9", "WXY");
}
private void foo() throws Exception
{
Scanner sc = new Scanner(new FileReader(new File("data/namenum.in")));
out = new PrintWriter(new BufferedWriter(new FileWriter(
"data/namenum.out")));
while(sc.hasNext())
{
flag=false;
sb=new StringBuilder();
c=sc.next().toCharArray();
too("",0);
if(!flag)
out.println("NONE");
else
out.print(sb);
}
out.close();
sc.close();
}
private void too(String s,int i)
{
if(i==c.length)
{
if(dict.contains(s))
{
sb.append(s+"\n");
flag=true;
}
return;
}
String str=map.get(""+c[i]);
too(s+str.charAt(0),i+1);
too(s+str.charAt(1),i+1);
too(s+str.charAt(2),i+1);
}
}
将每个输入映射成对应的字符串，并对比是否存在文件中。第十个case超时。
编号最多为12位数字，最多有3^12种可能，当文件中的字符串存储在哈希表中时，时间复杂度O（3^n）*O（1）。
考虑文件中的字符串仅仅不到5000，先将其转为数字字符串，时间复杂度O（M*N），其中M为文件中字符串个数小于5000.
以这些字符串转换后的值为key，原值为value存进hashmap。考虑到一串数字字符串可以对应多个值，所以键值对中的值使用集合。因为输出要有序，考虑treeset。
代码如下，最坏情况下时间比上面方法节省60%
package chapter1_2;
/*
ID: chicc991
LANG: JAVA
TASK: namenum
*/
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.Scanner;
import java.util.TreeSet;
public class namenum
{
private HashMap<String, TreeSet<String>> dict;
private HashMap<String, String> map;
public static void main(String[] args) throws Exception
{
namenum main = new namenum();
}
public namenum() throws Exception
{
init();
too();
}
private void init() throws Exception
{
Scanner sc = new Scanner(new FileReader(new File("data/dict.txt")));
dict = new HashMap<String, TreeSet<String>>();
map = new HashMap<String, String>();
map.put("A", "2");
map.put("B", "2");
map.put("C", "2");
map.put("D", "3");
map.put("E", "3");
map.put("F", "3");
map.put("G", "4");
map.put("H", "4");
map.put("I", "4");
map.put("J", "5");
map.put("K", "5");
map.put("L", "5");
map.put("M", "6");
map.put("N", "6");
map.put("O", "6");
map.put("P", "7");
map.put("R", "7");
map.put("S", "7");
map.put("T", "8");
map.put("U", "8");
map.put("V", "8");
map.put("W", "9");
map.put("X", "9");
map.put("Y", "9");
while (sc.hasNext()) {
String strValue = sc.next();
String strKey = foo(strValue.toCharArray());
TreeSet<String> arr;
if (dict.containsKey(strKey))
arr = dict.get(strKey);
else
arr = new TreeSet<String>();
arr.add(strValue);
dict.put(strKey, arr);
}
}
private String foo(char[] c)
{
String s = "";
for (int i = 0; i < c.length; i++)
s += map.get(c[i] + "");
return s;
}
private void too() throws Exception
{
Scanner sc = new Scanner(new FileReader(new File("data/namenum.in")));
PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter(
"data/namenum.out")));
while (sc.hasNext()) {
String str = sc.next();
if (dict.containsKey(str)) {
TreeSet<String> arr = dict.get(str);
while (!arr.isEmpty())
out.println(arr.pollFirst());
} else
out.println("NONE");
}
out.close();
sc.close();
}
}
palsquare
package chapter1_2;
/*
ID: chicc991
LANG: JAVA
TASK: palsquare
*/
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.Scanner;
public class palsquare
{
private PrintWriter out;
public static void main(String[] args) throws Exception
{
palsquare main = new palsquare();
}
public palsquare() throws Exception
{
Scanner sc = new Scanner(new FileReader(new File("data/palsquare.in")));
out = new PrintWriter(new BufferedWriter(new FileWriter(
"data/palsquare.out")));
while (sc.hasNext()) {
int b = sc.nextInt();
for (int i = 1; i <= 300; i++) {
Palindrome(i, b);
}
}
out.close();
sc.close();
}
private void Palindrome(int a, int b)
{
String s = change(a * a, b);
if (isPalindrome(s)) {
out.println(change(a, b) + " " + s);
}
}
private String change(int a, int b)
{
String str = "";
int r;
while (true) {
if (a == 0)
break;
else {
r = a % b;
a = a / b;
str = foo(r, b) + str;
}
}
return str;
}
private String foo(int r, int b)
{
if (r < 10)
return r + "";
else {
char a = (char) (r - 10 + 'A');
return a + "";
}
}
private boolean isPalindrome(String s)
{
char[] c = s.toCharArray();
int i = 0;
int j = s.length() - 1;
while (i <= j) {
if (c[i++] != c[j--])
return false;
}
return true;
}
}
简单题，注意
char a = (char) (r - 10 + 'A');如果直接输出r-10+'A',则输出时对应的ascii码
dualpal
package chapter1_2;
/*
ID: chicc991
LANG: JAVA
TASK: dualpal
*/
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.Scanner;
public class dualpal
{
private Scanner sc;
private PrintWriter out;
public static void main(String[] args) throws Exception
{
dualpal main = new dualpal();
}
public dualpal() throws Exception
{
sc = new Scanner(new FileReader(new File("data/dualpal.in")));
out = new PrintWriter(new BufferedWriter(new FileWriter(
"data/dualpal.out")));
while (sc.hasNext()) {
int n = sc.nextInt();
int s = sc.nextInt();
foo(n,s);
}
out.close();
sc.close();
}
private void foo(int n, int s)
{
int i=s+1;
while(n>0)
{
if(isDualpal(i))
{
n--;
out.println(i);
}
i++;
}
}
//判断i是否在至少2种进制中时回文数
private boolean isDualpal(int i)
{
int flag=0;
for(int j=2;j<=10;j++)
{
if(isPalindrome(change(i,j)))
flag++;
if(flag==2)
return true;
}
return false;
}
//判断是否是回文数
private boolean isPalindrome(String str)
{
char[] c=str.toCharArray();
if(c[0]=='0')
return false;
int i=0;
int j=c.length-1;
while(i<=j)
{
if(c[i++]!=c[j--])
return false;
}
return true;
}
//将10进制s转化为b进制，返回对应字符串
private String change(int s, int b)
{
String str = "";
int r;
while (true) {
if (s == 0)
break;
r = s % b;
s = s / b;
str = r + str;
}
return str;
}
}
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