如题所述
é¢è¯-javaç®æ³é¢ï¼
1.ç¼åä¸ä¸ªç¨åºï¼è¾å ¥n,æ±nï¼ï¼ç¨éå½çæ¹å¼å®ç°ï¼ã
public static long fac(int n){ if(n<=0) return 0; else if(n==1) return 1; else return n*fac(n-1);
} public static void main(String [] args) {
System.out.println(fac(6));
}
2.ç¼åä¸ä¸ªç¨åºï¼æ1ï¼2,3,4个æ°åï¼è½ç»æå¤å°ä¸ªäºä¸ç¸åä¸æ éå¤æ°åçä¸ä½æ°ï¼é½æ¯å¤å°ï¼
public static void main(String [] args) { int i, j, k; int m=0; for(i=1;i<=4;i++) for(j=1;j<=4;j++) for(k=1;k<=4;k++){ if(i!=j&&k!=j&&i!=k){
System.out.println(""+i+j+k);
m++;
}
}
System.out.println("è½ç»æï¼"+m+"个");
}
3.ç¼åä¸ä¸ªç¨åºï¼å°text1.txtæ件ä¸çåè¯ä¸text2.txtæ件ä¸çåè¯äº¤æ¿å并å°text3.txtæ件ä¸ãtext1.txtæ件ä¸çåè¯ç¨å车符åéï¼text2.txtæ件ä¸ç¨å车æç©ºæ ¼è¿è¡åéã
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
public class text{
public static void main(String[] args) throws Exception{
String[] a = getArrayByFile("text1.txt",new char[]{'\n'});
String[] b = getArrayByFile("text2.txt",new char[]{'\n',' '});
FileWriter c = new FileWriter("text3.txt");
int aIndex=0; int bIndex=0;
while(aIndex<a.length){
c.write(a[aIndex++] + "\n");
if(bIndex<b.length)
c.write(b[bIndex++] + "\n");
}
while(bIndex<b.length){
c.write(b[bIndex++] + "\n");
}
c.close();
}
public static String[] getArrayByFile(String filename,char[] seperators) throws Exception{
File f = new File(filename);
FileReader reader = new FileReader(f);
char[] buf = new char[(int)f.length()];
int len = reader.read(buf);
String results = new String(buf,0,len);
String regex = null;
if(seperators.length >1 ){
regex = "" + seperators[0] + "|" + seperators[1];
}else{
regex = "" + seperators[0];
}
return results.split(regex);
}
}
4.639172æ¯ä¸ªä½æ°ä¸çæ°åé½æ¯ä¸åçï¼ä¸å¹³æ¹åæå¾æ°åçææä½æ°é½ä¸ä¼åºç°ç»æå®èªèº«çæ°åãï¼639172*639172=408540845584ï¼ï¼ç±»ä¼¼äº639172è¿æ ·ç6ä½æ°è¿æå 个ï¼åå«æ¯ä»ä¹ï¼
è¿é¢éç¨çHashMapç»æå¤æææ éå¤ï¼ä¹å¯ä»¥éç¨ä¸é¢çæ°ç»å¤æã
public void selectNum(){
for(long n = 100000; n <= 999999;n++){
if(isSelfRepeat(n)) //æç¸åçæ°åï¼åè·³è¿
continue;
else if(isPingFangRepeat(n*n,n)){ //该æ°çå¹³æ¹ä¸æ¯å¦æä¸è¯¥æ°ç¸åçæ°å
continue;
} else{ //符åæ¡ä»¶ï¼åæå° System.out.println(n);
}
}
} public boolean isSelfRepeat(long n){
HashMap<Long,String> m=new HashMap<Long,String>(); //åå¨çæ¶åå¤æææ éå¤å¼
while(n!=0){ if(m.containsKey(n%10)){ return true;
} else{
m.put(n%10,"1");
}
n=n/10;
} return false;
} public boolean isPingFangRepeat(long pingfang,long n){
HashMap<Long,String> m=new HashMap<Long,String>(); while(n!=0){
m.put(n%10,"1");
n=n/10;
} while(pingfang!=0){ if(m.containsKey(pingfang%10)){ return true;
}
pingfang=pingfang/10;
} return false;
} public static void main(String args[]){ new test().selectNum();
}
5.æ¯å¦ï¼968548+968545=321732732å®ççæ¡é没æåé¢ä¸¤ä¸ªæ°éçæ°åï¼æå¤å°è¿æ ·ç6ä½æ°ã
public void selectNum(){
for(int n = 10; n <= 99;n++){
for(int m = 10; m <= 99;m++){ if(isRepeat(n,m)){ continue;
} else{
System.out.println("ç»åæ¯"+n+","+m);
}
}
}
} public boolean isRepeat(int n,int m){ int[] a={0,0,0,0,0,0,0,0,0,0}; int s=n+m; while(n!=0){
a[n%10]=1;
n=n/10;
} while(m!=0){
a[m%10]=1;
m=m/10;
} while(s!=0){ if(a[s%10]==1){ return true;
}
s=s/10;
} return false;
} public static void main(String args[]){ new test().selectNum();
}
6.ç»å®String,æ±æ¤å符串çåè¯æ°éãå符串ä¸å æ¬æ ç¹ï¼å¤§ååæ¯ãä¾å¦ String str="hello world hello hi";åè¯æ°é为3ï¼åå«æ¯ï¼hello world hiã
public static void main(String [] args) { int count = 0;
String str="hello world hello hi";
String newStr="";
HashMap<String,String> m=new HashMap<String,String>();
String [] a=str.split(" "); for (int i=0;i<a.length;i++){ if(!m.containsKey(a[i])){
m.put(a[i],"1");
count++;
newStr=newStr+" "+a[i];
}
}
System.out.println("è¿æ®µçæåè¯ç个æ°æ¯ï¼"+count+","+newStr);
}
7.ååºç¨åºè¿è¡ç»æã
public class Test1 { private static void test(int[]arr) { for (int i = 0; i < arr.length; i++) { try { if (arr[i] % 2 == 0) { throw new NullPointerException();
} else {
System.out.print(i);
}
} catch (Exception e) {
System.out.print("a ");
} finally {
System.out.print("b ");
}
}
}
public static void main(String[]args) { try {
test(new int[] {0, 1, 2, 3, 4, 5});
} catch (Exception e) {
System.out.print("c ");
}
}
}
è¿è¡ç»æï¼a b 1b a b 3b a b 5b
public class Test1 { private static void test(int[]arr) { for (int i = 0; i < arr.length; i++) { try { if (arr[i] % 2 == 0) { throw new NullPointerException();
} else {
System.out.print(i);
}
}
finally {
System.out.print("b ");
}
}
}
public static void main(String[]args) { try {
test(new int[] {0, 1, 2, 3, 4, 5});
} catch (Exception e) {
System.out.print("c ");
}
}
}
è¿è¡ç»æï¼b c
8.åè¯æ°
ç»è®¡ä¸ç¯æç« éä¸ååè¯çæ»æ°ã
Input
æå¤ç»æ°æ®ï¼æ¯ç»ä¸è¡ï¼æ¯ç»å°±æ¯ä¸ç¯å°æç« ãæ¯ç¯å°æç« é½æ¯ç±å°ååæ¯åç©ºæ ¼ç»æï¼æ²¡ææ ç¹ç¬¦å·ï¼éå°#æ¶è¡¨ç¤ºè¾å ¥ç»æã
Output
æ¯ç»å¼è¾åºä¸ä¸ªæ´æ°ï¼å ¶åç¬æè¡ï¼è¯¥æ´æ°ä»£è¡¨ä¸ç¯æç« éä¸ååè¯çæ»æ°ã
Sample Input
you are my friend
#
Sample Output
4
public static void main(String [] args) {
List<Integer> countList=new ArrayList<Integer>(); int count;
HashMap<String,String> m;
String str; //读åé®çè¾å ¥çä¸è¡ï¼ä»¥å车æ¢è¡ä¸ºç»æè¾å ¥ï¼ String[] a;
Scanner in=new Scanner(System.in);
while( !(str=in.nextLine()).equals("#") ){
a=str.split(" ");
m=new HashMap<String,String>();
count = 0; for (int i=0;i<a.length;i++){ if(!m.containsKey(a[i]) && (!a[i].equals(""))){
m.put(a[i],"1");
count++;
}
}
countList.add(count);
}s for(int c:countList)
System.out.println(c);
}
1.ç¼åä¸ä¸ªç¨åºï¼è¾å ¥n,æ±nï¼ï¼ç¨éå½çæ¹å¼å®ç°ï¼ã
public static long fac(int n){ if(n<=0) return 0; else if(n==1) return 1; else return n*fac(n-1);
} public static void main(String [] args) {
System.out.println(fac(6));
}
2.ç¼åä¸ä¸ªç¨åºï¼æ1ï¼2,3,4个æ°åï¼è½ç»æå¤å°ä¸ªäºä¸ç¸åä¸æ éå¤æ°åçä¸ä½æ°ï¼é½æ¯å¤å°ï¼
public static void main(String [] args) { int i, j, k; int m=0; for(i=1;i<=4;i++) for(j=1;j<=4;j++) for(k=1;k<=4;k++){ if(i!=j&&k!=j&&i!=k){
System.out.println(""+i+j+k);
m++;
}
}
System.out.println("è½ç»æï¼"+m+"个");
}
3.ç¼åä¸ä¸ªç¨åºï¼å°text1.txtæ件ä¸çåè¯ä¸text2.txtæ件ä¸çåè¯äº¤æ¿å并å°text3.txtæ件ä¸ãtext1.txtæ件ä¸çåè¯ç¨å车符åéï¼text2.txtæ件ä¸ç¨å车æç©ºæ ¼è¿è¡åéã
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
public class text{
public static void main(String[] args) throws Exception{
String[] a = getArrayByFile("text1.txt",new char[]{'\n'});
String[] b = getArrayByFile("text2.txt",new char[]{'\n',' '});
FileWriter c = new FileWriter("text3.txt");
int aIndex=0; int bIndex=0;
while(aIndex<a.length){
c.write(a[aIndex++] + "\n");
if(bIndex<b.length)
c.write(b[bIndex++] + "\n");
}
while(bIndex<b.length){
c.write(b[bIndex++] + "\n");
}
c.close();
}
public static String[] getArrayByFile(String filename,char[] seperators) throws Exception{
File f = new File(filename);
FileReader reader = new FileReader(f);
char[] buf = new char[(int)f.length()];
int len = reader.read(buf);
String results = new String(buf,0,len);
String regex = null;
if(seperators.length >1 ){
regex = "" + seperators[0] + "|" + seperators[1];
}else{
regex = "" + seperators[0];
}
return results.split(regex);
}
}
4.639172æ¯ä¸ªä½æ°ä¸çæ°åé½æ¯ä¸åçï¼ä¸å¹³æ¹åæå¾æ°åçææä½æ°é½ä¸ä¼åºç°ç»æå®èªèº«çæ°åãï¼639172*639172=408540845584ï¼ï¼ç±»ä¼¼äº639172è¿æ ·ç6ä½æ°è¿æå 个ï¼åå«æ¯ä»ä¹ï¼
è¿é¢éç¨çHashMapç»æå¤æææ éå¤ï¼ä¹å¯ä»¥éç¨ä¸é¢çæ°ç»å¤æã
public void selectNum(){
for(long n = 100000; n <= 999999;n++){
if(isSelfRepeat(n)) //æç¸åçæ°åï¼åè·³è¿
continue;
else if(isPingFangRepeat(n*n,n)){ //该æ°çå¹³æ¹ä¸æ¯å¦æä¸è¯¥æ°ç¸åçæ°å
continue;
} else{ //符åæ¡ä»¶ï¼åæå° System.out.println(n);
}
}
} public boolean isSelfRepeat(long n){
HashMap<Long,String> m=new HashMap<Long,String>(); //åå¨çæ¶åå¤æææ éå¤å¼
while(n!=0){ if(m.containsKey(n%10)){ return true;
} else{
m.put(n%10,"1");
}
n=n/10;
} return false;
} public boolean isPingFangRepeat(long pingfang,long n){
HashMap<Long,String> m=new HashMap<Long,String>(); while(n!=0){
m.put(n%10,"1");
n=n/10;
} while(pingfang!=0){ if(m.containsKey(pingfang%10)){ return true;
}
pingfang=pingfang/10;
} return false;
} public static void main(String args[]){ new test().selectNum();
}
5.æ¯å¦ï¼968548+968545=321732732å®ççæ¡é没æåé¢ä¸¤ä¸ªæ°éçæ°åï¼æå¤å°è¿æ ·ç6ä½æ°ã
public void selectNum(){
for(int n = 10; n <= 99;n++){
for(int m = 10; m <= 99;m++){ if(isRepeat(n,m)){ continue;
} else{
System.out.println("ç»åæ¯"+n+","+m);
}
}
}
} public boolean isRepeat(int n,int m){ int[] a={0,0,0,0,0,0,0,0,0,0}; int s=n+m; while(n!=0){
a[n%10]=1;
n=n/10;
} while(m!=0){
a[m%10]=1;
m=m/10;
} while(s!=0){ if(a[s%10]==1){ return true;
}
s=s/10;
} return false;
} public static void main(String args[]){ new test().selectNum();
}
6.ç»å®String,æ±æ¤å符串çåè¯æ°éãå符串ä¸å æ¬æ ç¹ï¼å¤§ååæ¯ãä¾å¦ String str="hello world hello hi";åè¯æ°é为3ï¼åå«æ¯ï¼hello world hiã
public static void main(String [] args) { int count = 0;
String str="hello world hello hi";
String newStr="";
HashMap<String,String> m=new HashMap<String,String>();
String [] a=str.split(" "); for (int i=0;i<a.length;i++){ if(!m.containsKey(a[i])){
m.put(a[i],"1");
count++;
newStr=newStr+" "+a[i];
}
}
System.out.println("è¿æ®µçæåè¯ç个æ°æ¯ï¼"+count+","+newStr);
}
7.ååºç¨åºè¿è¡ç»æã
public class Test1 { private static void test(int[]arr) { for (int i = 0; i < arr.length; i++) { try { if (arr[i] % 2 == 0) { throw new NullPointerException();
} else {
System.out.print(i);
}
} catch (Exception e) {
System.out.print("a ");
} finally {
System.out.print("b ");
}
}
}
public static void main(String[]args) { try {
test(new int[] {0, 1, 2, 3, 4, 5});
} catch (Exception e) {
System.out.print("c ");
}
}
}
è¿è¡ç»æï¼a b 1b a b 3b a b 5b
public class Test1 { private static void test(int[]arr) { for (int i = 0; i < arr.length; i++) { try { if (arr[i] % 2 == 0) { throw new NullPointerException();
} else {
System.out.print(i);
}
}
finally {
System.out.print("b ");
}
}
}
public static void main(String[]args) { try {
test(new int[] {0, 1, 2, 3, 4, 5});
} catch (Exception e) {
System.out.print("c ");
}
}
}
è¿è¡ç»æï¼b c
8.åè¯æ°
ç»è®¡ä¸ç¯æç« éä¸ååè¯çæ»æ°ã
Input
æå¤ç»æ°æ®ï¼æ¯ç»ä¸è¡ï¼æ¯ç»å°±æ¯ä¸ç¯å°æç« ãæ¯ç¯å°æç« é½æ¯ç±å°ååæ¯åç©ºæ ¼ç»æï¼æ²¡ææ ç¹ç¬¦å·ï¼éå°#æ¶è¡¨ç¤ºè¾å ¥ç»æã
Output
æ¯ç»å¼è¾åºä¸ä¸ªæ´æ°ï¼å ¶åç¬æè¡ï¼è¯¥æ´æ°ä»£è¡¨ä¸ç¯æç« éä¸ååè¯çæ»æ°ã
Sample Input
you are my friend
#
Sample Output
4
public static void main(String [] args) {
List<Integer> countList=new ArrayList<Integer>(); int count;
HashMap<String,String> m;
String str; //读åé®çè¾å ¥çä¸è¡ï¼ä»¥å车æ¢è¡ä¸ºç»æè¾å ¥ï¼ String[] a;
Scanner in=new Scanner(System.in);
while( !(str=in.nextLine()).equals("#") ){
a=str.split(" ");
m=new HashMap<String,String>();
count = 0; for (int i=0;i<a.length;i++){ if(!m.containsKey(a[i]) && (!a[i].equals(""))){
m.put(a[i],"1");
count++;
}
}
countList.add(count);
}s for(int c:countList)
System.out.println(c);
}
温馨提示:答案为网友推荐,仅供参考