Table of contents
10. Convert decimal to hexadecimal
import java.util.Scanner;
//法一：100分
public class 十进制转十六进制_10 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
// System.out.println(Integer.toBinaryString(n)); //二进制
// System.out.println(Integer.toOctalString(n));//八进制
System.out.println(Integer.toHexString(n).toUpperCase()); //十六进制
}
}
11. Convert hexadecimal to decimal
import java.math.BigInteger;
import java.util.Scanner;
//法1： 100分
public class 十六进制转十进制_11 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String str = sc.nextLine();
String Oct=new BigInteger(str, 16).toString(10);
System.out.println(Oct);
}
}
12. Convert hexadecimal to octal
import java.math.BigInteger;
import java.util.Scanner;
//法1： 100分
public class 十六进制转八进制_12 {
/* 给定n个十六进制正整数，输出它们对应的八进制数。 */
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
//获取n
int n=sc.nextInt();
//定义数组来存放转换后的数
String []arr=new String[n];
//循环然后进行16进制转换为8进制
for(int i=0;i<n;i++) {
//获取16进制数（注意next和nextInt区别）
String sixteen=sc.next();
//由于数字可能会越界，所有使用BigInteger的api
//new BigInteger(number, from).toString(to);
//number:要转换的数 from:原数的进制 to:要转换成的进制
String eight=new BigInteger(sixteen, 16).toString(8);
//将结果存入arr中
arr[i]=eight;
}
//遍历数组并打印
for(int i=0;i<n;i++) {
System.out.println(arr[i]);
}
}
}
13. Array sorting
import java.util.Scanner;
public class 数列排序_13 {
public static void main(String a[]) {
Scanner in = new Scanner(System.in);
int n=in.nextInt();
int f[] =new int[n];
for (int i = 0; i < n; i++) {
f[i]=in.nextInt();
}
int b = 0;
for(int i =0;i<n-1;i++) {
for(int j = i+1;j<n;j++) {
if(f[i]>f[j]) {
b = f[i];
f[i] = f[j];
f[j] = b;
}
}
}
for(int i =0;i<n;i++) {
System.out.printf("%d ",f[i]);
}
}
}
14. Time conversion
import java.util.Scanner;
public class 时间转换_14 {
public static void main(String a[]) {
Scanner in = new Scanner(System.in);
int n=in.nextInt();
int H=n/3600;
int M=(n-H*3600)/60;
int S=(n-H*3600)-60*M;
System.out.print(H+":"+M+":"+S);
}
}
15. String comparison
import java.util.Scanner;
public class 字符串比较_15 {
public static void main(String a[]) {
Scanner in = new Scanner(System.in);
String []arr=new String[2];
for (int i = 0; i < arr.length; i++) {
arr[i]=in.next();
}
if(arr[0].length()!=arr[1].length())
{
System.out.print("1");
}else {
if(arr[0].equals(arr[1]) ){
System.out.print("2");
}else if (arr[0].toUpperCase().equals(arr[1].toUpperCase())) {
System.out.print("3");
}else {
System.out.print("4");
}
}
}
}
16. Decompose prime factor
import java.util.Scanner;
public class 分解质因数_16 {
//质数： 质数又称素数。一个大于1的自然数，除了1和它自身外，不能被其他自然数整除的数叫做质数；否则称为合数。
//0和1既不是质数也不是合数，最小的质数是2
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int a = in.nextInt();
int b = in.nextInt();
for(;a<=b;a++){
int temp = a;
boolean flag = false;
System.out.print(temp+"=");
while(temp!=1){
for(int i=2;i<=temp;i++){
if(isPrime(i)&&temp%i==0){
if(flag){
System.out.print("*"+i);
}else{
flag = true;
System.out.print(i);
}
temp /= i;
break;
}
}
}
System.out.println();
}
}
public static boolean isPrime(int n){
if(n<2)return false;
if(n==2)return true;
if(n%2==0)return false;
for(int i=3;i*i<=n;i+=2){
if(n%i==0){
return false;
}
}
return true;
}
}
17. Matrix multiplication
import java.util.Scanner;
public class 矩阵乘法_17 {
private static int N;//矩阵A的阶数
private static int[][] matrix; //矩阵A
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
N = sc.nextInt();
int M = sc.nextInt(); //要求的幂数
matrix = new int[N][N]; //原矩阵
//输入矩阵数据
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
matrix[i][j] = sc.nextInt();
}
}
//新矩阵
int[][] newMatrix = new int[N][N];
//幂数为0的情况
if (M == 0) {
for (int i = 0; i < N; i++) {
newMatrix[i][i] = 1;
}
//幂数不为0的情况
} else {
newMatrix = matrix;
for (int i = 0; i < M - 1; i++) {
newMatrix = matriMultiplication(newMatrix);
}
}
//输出新矩阵
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
System.out.print(newMatrix[i][j] + " ");
}
System.out.println();
}
}
private static int[][] matriMultiplication(int[][] matrixParam) {
int[][] newMatrix = new int[N][N];
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
for (int k = 0; k < N; k++) {
newMatrix[i][j] += matrixParam[i][k] * matrix[k][j];
}
}
}
return newMatrix;
}
}
18. Rectangular area intersection
import java.util.Scanner;
public class 矩形面积交_18 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
//获得四个点的坐标
double x1 = sc.nextDouble(),y1=sc.nextDouble(),x2=sc.nextDouble(),y2 = sc.nextDouble();
double x3 = sc.nextDouble(),y3=sc.nextDouble(),x4=sc.nextDouble(),y4 = sc.nextDouble();
//关闭Scanner方法
sc.close();
//找出矩形一的最大最小值x,最大最小y
double maxx = Math.max(x1,x2);
double minx = Math.min(x1, x2);
double maxy = Math.max(y1, y2);
double miny =Math.min(y1, y2);
//找出矩形二的最大最小值x,最大最小y
double bigx = Math.max(x3,x4);
double smax = Math.min(x3, x4);
double bigy = Math.max(y3, y4);
double smay =Math.min(y3, y4);
//判断是否相离或者相切
if(smax>=maxx||minx>=bigx ||smay>=maxy||miny>=bigy){
System.out.println("0.00");
}else{
//找出相交的矩形的两个点，点1（xx,yy） 点2（x，y）
double xx = Math.max(minx, smax),yy=Math.max(miny, smay);
double x = Math.min(maxx, bigx),y=Math.min(maxy, bigy);
System.out.println(String.format("%.2f", (Math.abs(x-xx)*Math.abs(y-yy))));
}
}
}
19. The price of perfection
package a;
import java.util.Scanner;
public class 完美的代价_19 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
String str = sc.next();
//将输入字符串转换为char数组
char[] charArr = str.toCharArray();
//求出现的次数为奇数的字母个数
int[] num = new int[26];
//记录每个字母出现的个数
for(int i = 0; i < n; i++) {
num[charArr[i] - 'a']++;
}
//出现次数为奇数的字母个数
int count = 0;
for(int i = 0; i < 26; i++) {
if(num[i] != 0) {
if(num[i] % 2 != 0) {
count++;
}
}
}
//若个数大于等于2个,则直接返回Impossible
if(count >= 2) {
System.out.println("Impossible");
}else{
System.out.println(getCount(str));
}
}
static int getCount(String str) {
//1,2长度是无需交换
if(str.length()==1 || str.length()==2) return 0;
//取字符串第一个字符最后一次出现的位置
int temp = str.lastIndexOf(str.charAt(0));
if(temp==0){
return str.length()/2 + getCount(str.substring(1,str.length()));
} else {
//0号位字符和已找到temp位置的字符都移除,然后进行递归
//String remoStr = str.substring(1, temp) + str.substring(temp + 1,str.length()); //这么写不知道那组数据不对
StringBuilder strBuilder = new StringBuilder(str);
strBuilder.deleteCharAt(temp);
strBuilder.deleteCharAt(0);
//System.out.println(temp +".."+ remoStr);
return str.length()-temp-1 + getCount(strBuilder.toString());
}
}
}