[Algorithm] Array 문제
1.큰 수 출력
import java.util.*;
class Main {
public ArrayList<Integer> solution(int n, int[] arr){
ArrayList<Integer> answer = new ArrayList<Integer>();
answer.add(arr[0]); //맨앞자리는 고정으로 들어가니까
for(int i =1; i<n;i++) {
if(arr[i]>arr[i-1]) {
answer.add(arr[i]);
}
}
return answer;
}
public static void main(String[] args){
Main T = new Main();
Scanner sc = new Scanner(System.in);
int n=sc.nextInt();
int [] arr = new int [n];
for(int i =0; i<n ;i++) {
arr[i] = sc.nextInt();
}
for(int x: T.solution(n, arr)) {
System.out.print(x+" ");
}
}
}
2.보이는 학생
import java.util.*;
class Main {
public int solution(int n, int[] arr){
int answer=1, max=arr[0];
for(int i=1; i<n; i++){
if(arr[i]>max){
max=arr[i];
answer++;
}
}
return answer;
}
public static void main(String[] args){
Main T = new Main();
Scanner sc = new Scanner(System.in);
int n=sc.nextInt();
int[] arr=new int[n];
for(int i=0; i<n; i++){
arr[i]=sc.nextInt();
}
System.out.print(T.solution(n, arr));
}
}
3.가위바위보
import java.util.*;
class Main {
public String solution(int n, int[] a, int[] b){
String answer="";
for(int i=0; i<n; i++){
if(a[i]==b[i]) answer+="D";
else if(a[i]==1 && b[i]==3) answer+="A";
else if(a[i]==2 && b[i]==1) answer+="A";
else if(a[i]==3 && b[i]==2) answer+="A";
else answer+="B";
}
return answer;
}
public static void main(String[] args){
Main T = new Main();
Scanner kb = new Scanner(System.in);
int n=kb.nextInt();
int[] a=new int[n];
int[] b=new int[n];
for(int i=0; i<n; i++){
a[i]=kb.nextInt();
}
for(int i=0; i<n; i++){
b[i]=kb.nextInt();
}
for(char x : T.solution(n, a, b).toCharArray()) System.out.println(x);
}
}
4.피보나치 수열
import java.util.*;
class Main {
public int[] solution(int n){
int[] answer=new int[n];
answer[0]=1;
answer[1]=1;
for(int i=2; i<n; i++){
answer[i]=answer[i-2]+answer[i-1];
}
return answer;
}
public static void main(String[] args){
Main T = new Main();
Scanner sc = new Scanner(System.in);
int n=sc.nextInt();
for(int x :T.solution(n)) System.out.print(x+" ");
}
}
import java.util.*;
class Main { //배열 안 쓰고 풀어야 할 경우.
public void solution(int n){
int a=1, b=1, c;
System.out.print(a+" "+b+" ");
for(int i=2; i<n; i++){
c=a+b;
System.out.print(c+" ");
a=b;
b=c;
}
}
public static void main(String[] args){
Main T = new Main();
Scanner sc = new Scanner(System.in);
int n=sc.nextInt();
T.solution(n);
}
}
5.소수(에라토스테네스)
import java.util.*;
class Main {
public int solution(int n){
int cnt=0;
int[] ch = new int[n+1];
for(int i=2; i<=n; i++){
if(ch[i]==0){
cnt++;
for(int j=i; j<=n; j=j+i)
ch[j]=1;
}
}
return cnt;
}
public static void main(String[] args){
Main T = new Main();
Scanner sc = new Scanner(System.in);
int n=sc.nextInt();
System.out.println(T.solution(n));
}
}
6.뒤집은 소수
import java.util.*;
class Main {
public boolean isPrime(int num){
if(num==1) return false;
for(int i=2; i<num; i++){
if(num%i==0) return false;
}
return true;
}
public ArrayList<Integer> solution(int n, int[] arr){
ArrayList<Integer> answer = new ArrayList<>();
for(int i=0; i<n; i++){
int tmp=arr[i];
int res=0;
while(tmp>0){
int t=tmp%10;
res=res*10+t;
tmp=tmp/10;
}
if(isPrime(res)) answer.add(res);
}
return answer;
}
public static void main(String[] args){
Main T = new Main();
Scanner sc = new Scanner(System.in);
int n=sc.nextInt();
int[] arr=new int[n];
for(int i=0; i<n; i++){
arr[i]=sc.nextInt();
}
for(int x : T.solution(n, arr)){
System.out.print(x+" ");
}
}
}
7.점수계산
import java.util.*;
class Main {
public int solution(int n, int[] arr){
int answer=0, cnt=0;
for(int i=0; i<n; i++){
if(arr[i]==1){
cnt++;
answer+=cnt;
}
else cnt=0;
}
return answer;
}
public static void main(String[] args){
Main T = new Main();
Scanner sc = new Scanner(System.in);
int n=sc.nextInt();
int[] arr=new int[n];
for(int i=0; i<n; i++){
arr[i]=sc.nextInt();
}
System.out.print(T.solution(n, arr));
}
}
8.등수 구하기
import java.util.*;
class Main {
public int[] solution(int n, int[] arr){
int[] answer = new int[n];
for(int i=0; i<n; i++){
int cnt=1;
for(int j=0; j<arr.length; j++){
if(arr[j]>arr[i]) cnt++;
}
answer[i]=cnt;
}
return answer;
}
public static void main(String[] args){
Main T = new Main();
Scanner sc = new Scanner(System.in);
int n=sc.nextInt();
int[] arr=new int[n];
for(int i=0; i<n; i++){
arr[i]=sc.nextInt();
}
for(int x :T.solution(n, arr)) System.out.print(x+" ");
}
}
9.격자판 최대합
import java.util.*;
class Main {
public int solution(int n, int[][] arr){
int answer=-2147000000;
int sum1=0, sum2=0;
for(int i=0; i<n; i++){
sum1=sum2=0;
for(int j=0; j<n; j++){
sum1+=arr[i][j]; //행이 고정 열이 도는거
sum2+=arr[j][i]; //행이 돌고 열이 고정되는거.
}
answer=Math.max(answer, sum1);
answer=Math.max(answer, sum2);
}
sum1=sum2=0;
for(int i=0; i<n; i++){
sum1+=arr[i][i]; //우상향 대각선
sum2+=arr[i][n-i-1]; //우하향 대각선
}
answer=Math.max(answer, sum1);
answer=Math.max(answer, sum2);
return answer;
}
public static void main(String[] args){
Main T = new Main();
Scanner sc = new Scanner(System.in);
int n=sc.nextInt();
int[][] arr=new int[n][n];
for(int i=0; i<n; i++){
for(int j=0; j<n; j++){
arr[i][j]=sc.nextInt();
}
}
System.out.print(T.solution(n, arr));
}
}
10.봉우리
import java.util.*;
class Main {
int[] dx={-1, 0, 1, 0};
int[] dy={0, 1, 0, -1};
public int solution(int n, int[][] arr){
int answer=0;
for(int i=0; i<n; i++){
for(int j=0; j<n; j++){
boolean flag=true;
for(int k=0; k<4; k++){ //k는 4방향 더해주는거
int nx=i+dx[k]; //i 행번호
int ny=j+dy[k]; //j 열번호
if(nx>=0 && nx<n && ny>=0 && ny<n && arr[nx][ny]>=arr[i][j]){
//arr[nx][ny]는 4방향의 방향의 값이 4방향에 1개라도 있으면 false
//arr[nx][ny]>=arr[i][j] 이게 한번도 참이 안된건 상하좌우가 나보다 작다는 뜻 //그떄 봉우리니까 카운트
// nx>=0 && nx<n && ny>=0 && ny<n 이부분은 범위 벗어나는거(0으로 설정한 부분들을 참조해서 거기를 벗어나지 않게.
// arr[nx][ny]>=arr[i][j] 그리고 이부분이 뒤로가야됨 먼저 실행되면 안됨(범위설정이 먼저 실행되어야)
flag=false;
break;
}
}
if(flag) answer++; //그떄 봉우리니까 카운트
}
}
return answer;
}
public static void main(String[] args){
Main T = new Main();
Scanner sc = new Scanner(System.in);
int n=sc.nextInt();
int[][] arr=new int[n][n];
for(int i=0; i<n; i++){
for(int j=0; j<n; j++){
arr[i][j]=sc.nextInt();
}
}
System.out.print(T.solution(n, arr));
}
}
11.임시 반장 정하기
import java.util.*;
class Main {
public int solution(int n, int[][] arr){
int answer=0, max=0;
for(int i=1; i<=n; i++){
int cnt=0;
for(int j=1; j<=n; j++){
for(int k=1; k<=5; k++){
if(arr[i][k]==arr[j][k]){
cnt++;
break;
}
}
}
if(cnt>max){
max=cnt;
answer=i;
}
}
return answer;
}
public static void main(String[] args){
Main T = new Main();
Scanner sc = new Scanner(System.in);
int n=sc.nextInt();
int[][] arr=new int[n+1][6];
for(int i=1; i<=n; i++){
for(int j=1; j<=5; j++){
arr[i][j]=sc.nextInt();
}
}
System.out.print(T.solution(n, arr));
}
}
12.멘토링
import java.util.*;
class Main {
public int solution(int n, int m, int[][] arr){
int answer=0;
for(int i=1; i<=n; i++){
for(int j=1; j<=n; j++){
int cnt=0;
for(int k=0; k<m; k++){
int pi=0, pj=0;
for(int s=0; s<n; s++){
if(arr[k][s]==i) pi=s;
if(arr[k][s]==j) pj=s;
}
if(pi<pj) cnt++;
}
if(cnt==m){
answer++;
//System.out.println(i+" "+j);
}
}
}
return answer;
}
public static void main(String[] args){
Main T = new Main();
Scanner sc = new Scanner(System.in);
int n=sc.nextInt();
int m=sc.nextInt();
int[][] arr=new int[m][n];
for(int i=0; i<m; i++){
for(int j=0; j<n; j++){
arr[i][j]=sc.nextInt();
}
}
System.out.print(T.solution(n, m, arr));
}
}
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