[기초][JAVA][02.14] 프로그래머스 코딩테스트

n개 간격의 원소들

import java.util.*;

class Solution {
    public int[] solution(int[] num_list, int n) {
        int size = num_list.length/n;
        if(num_list.length%n>0){size++;}
        int[] answer = new int[size];
        
        int count = 0;
        for(int i = 0; i < num_list.length; i+=n){
            answer[count++]=num_list[i];
        }
        return answer;
    }
}

n 번째 원소까지

class Solution {
    public int[] solution(int[] num_list, int n) {
        int[] answer = new int[n];
        for(int i=0; i<n; i++){
            answer[i]=num_list[i];
        }
        return answer;
    }
}

순서 바꾸기

class Solution {
    public int[] solution(int[] num_list, int n) {
        int[] answer = new int[num_list.length];
        int count=0;
        for(int i = n; i < num_list.length; i++){
            answer[count++]=num_list[i];
        }
        for(int i = 0; i < n; i++){
            answer[count++]=num_list[i];
        }
        return answer;
    }
}

n 번째 원소부터

class Solution {
    public int[] solution(int[] num_list, int n) {
        int[] answer = new int[num_list.length-n+1];
        int count = 0;
        for(int i = n-1; i < num_list.length; i++){
            answer[count++]=num_list[i];
        }
        
        return answer;
    }
}

첫 번째로 나오는 음수

class Solution {
    public int solution(int[] num_list) {
        int answer = -1;
        for(int i = 0; i < num_list.length; i++){
            if(num_list[i]<0){
                answer=i;
                break;
            }
        }
        return answer;
    }
}

가까운 1 찾기

class Solution {
    public int solution(int[] arr, int idx) {
        int answer = -1;
        for(int i = idx; i<arr.length; i++){
            if(arr[i]==1){
                answer=i;
                break;
            }
        }
        return answer;
    }
}

카운트 다운

class Solution {
    public int[] solution(int start_num, int end_num) {
        int[] answer = new int[start_num-end_num+1];
        int count = 0;
        for(int i = start_num; i >= end_num; i--){
            answer[count++]=i;
        }
        return answer;
    }
}

배열 만들기 1

class Solution {
    public int[] solution(int n, int k) {
        int size = 0;
        for(int i = 1; i <= n; i++){
           if(k*i <=n){
               size++;
           } 
        }
        int[] answer = new int[size];
        for(int i = 0; i < size; i++){
            answer[i]=(i+1)*k;
        }
        return answer;
    }
}

접두사인지 확인하기

class Solution {
    public int solution(String my_string, String is_prefix) {
        int answer = 0;
        for(int i = 0; i < is_prefix.length(); i++){
            if(i<my_string.length()){
                if(my_string.charAt(i)==is_prefix.charAt(i)){
                    answer=1;
                }else{
                    answer= 0;
                    break;
                }
            }else{
                answer=0;
                break;
            }
        }
        return answer;
    }
}

문자열의 앞의 n글자

class Solution {
    public String solution(String my_string, int n) {
        String answer = "";
        for(int i = 0 ; i < n; i++){
            answer += my_string.charAt(i);
        }
        return answer;
    }
}

접미사 배열

import java.util.*;

class Solution {
    public String[] solution(String my_string) {
        String[] answer = new String[my_string.length()];
        int count = 0;
        for(int i = my_string.length()-1; i >=0; i--){
            String str = "";
            for(int j = my_string.length()-i-1; j<my_string.length(); j++){
                str+=my_string.charAt(j);
            }
            answer[count++]=str;
        }
        Arrays.sort(answer);
        
        return answer;
    }
}

문자열 뒤의 n글자

class Solution {
    public String solution(String my_string, int n) {
        String answer = "";
        for(int i = my_string.length()-n; i < my_string.length(); i++){
            answer += my_string.charAt(i);
        }
        return answer;
    }
}

부분 문자열 이어 붙여 문자열 만들기

class Solution {
    public String solution(String[] my_strings, int[][] parts) {
        String answer = "";
        for(int i = 0; i < parts.length; i++){
            for(int j = parts[i][0]; j <= parts[i][1]; j++){
                answer += my_strings[i].charAt(j);
            }
        }
        return answer;
    }
}

글자 이어 붙여 문자열 만들기

class Solution {
    public String solution(String my_string, int[] index_list) {
        String answer = "";
        for(int i = 0; i < index_list.length; i++){
            answer += my_string.charAt(index_list[i]);
        }
        return answer;
    }
}

콜라츠 수열 만들기

import java.util.*;

class Solution {
    public int[] solution(int n) {
        ArrayList<Integer> al = new ArrayList<>();
        al.add(n);
        while(n!=1){
            if(n%2==0){
                n /= 2;
                al.add(n);
            }else{
                n = 3 * n + 1;
                al.add(n);
            }
        }
        int[] answer = new int[al.size()];
        for(int i = 0; i < al.size(); i++){
            answer[i] = al.get(i).intValue();
        }
        return answer;
    }
}

카운트 업

class Solution {
    public int[] solution(int start_num, int end_num) {
        int[] answer = new int[end_num-start_num+1];
        int count = 0;
        for(int i = start_num; i <= end_num; i++){
            answer[count++]=i;
        }
        return answer;
    }
}

l로 만들기

class Solution {
    public String solution(String myString) {
        String answer = "";
        
        for(int i = 0; i < myString.length(); i++){
            if(myString.codePointAt(i)<"l".codePointAt(0)){
                answer+= "l";
            }else{
                answer+=myString.charAt(i);
            }
        }
        return answer;
    }
}

특별한 이차원 배열 1

class Solution {
    public int[][] solution(int n) {
        int[][] answer = new int[n][n];
        int j = 0;
        for(int i = 0; i < n; i++){
            answer[i][j++]=1;
        }
        return answer;
    }
}

간단한 식 계산하기

class Solution {
    public int solution(String binomial) {
        int answer = 0;
        String[] str = binomial.split(" ");
        if(str[1].codePointAt(0)=="+".codePointAt(0)){
            answer = Integer.parseInt(str[0]) + Integer.parseInt(str[2]);
            System.out.println(answer + "+");
        }else if(str[1].codePointAt(0)=="-".codePointAt(0)){
            answer = Integer.parseInt(str[0]) - Integer.parseInt(str[2]);
        }else{
            answer = Integer.parseInt(str[0]) * Integer.parseInt(str[2]);
        }
        return answer;
    }
}

주사위 게임 1

class Solution {
    public int solution(int a, int b) {
        int answer = 0;
        if(a%2!=0 && b%2!=0){
            answer = a*a + b*b;
        }else if(a%2!=0 || b%2!=0){
            answer = 2 * (a + b);
        }else{
            answer = a - b;
            if(answer < 0){
                answer *= -1;
            }
        }
        return answer;
    }
}

조건에 맞게 수열 변환하기 3

class Solution {
    public int[] solution(int[] arr, int k) {
        int[] answer = new int[arr.length];
        for(int i = 0; i < arr.length; i++){
            if(k%2!=0){
                answer[i]=arr[i]*k;   
            }else{
                answer[i]=arr[i]+k;   
            }
        }
        return answer;
    }
}

접미사인지 확인하기

class Solution {
    public int solution(String my_string, String is_suffix) {
        int answer = 0;
        int count = 0;
        if(my_string.length()<is_suffix.length()){
            return 0;
        }
        for(int i = my_string.length()-is_suffix.length(); i < my_string.length(); i++){
            if(my_string.charAt(i)==is_suffix.charAt(count++)){
                answer = 1;
            }else
                answer = 0;
        }
        return answer;
    }
}

9로 나눈 나머지

class Solution {
    public int solution(String number) {
        int answer = 0;
        String[] arr = number.split("");
        for(int i = 0; i < arr.length; i++){
            answer += Integer.parseInt(arr[i]);
        }
        answer%=9;
        
        return answer;
    }
}

배열의 원소 삭제하기

import java.util.*;

class Solution {
    public int[] solution(int[] arr, int[] delete_list) {
        ArrayList<Integer> al = new ArrayList<>();
        
        for(int i = 0; i < arr.length; i++){
            boolean b = true;
            for(int j = 0; j < delete_list.length; j++){
                if(delete_list[j]==arr[i]){
                    b = false;
                } 
            }
            if(b){
                al.add(arr[i]);
            }
        }
        
        int[] answer = new int[al.size()];
        for(int i = 0; i < answer.length; i++){
            answer[i]=al.get(i);
        }
        return answer;
    }
}

공백으로 구분하기 1

class Solution {
    public String[] solution(String my_string) {
        String[] answer = my_string.split(" ");
        return answer;
    }
}

부분 문자열

class Solution {
    public int solution(String str1, String str2) {
        int answer = 0;
        if(str2.contains(str1)){
            answer = 1;
        }
        return answer;
    }
}

꼬리 문자열

class Solution {
    public String solution(String[] str_list, String ex) {
        String answer = "";
        for(int i = 0; i < str_list.length; i++){
            if(!str_list[i].contains(ex)){
                answer += str_list[i];
            }
        }
        return answer;
    }
}

x 사이의 개수

class Solution {
    public int[] solution(String myString) {
        String[] arr = myString.split("x");
        int size = arr.length;
        if(myString.charAt(myString.length()-1)==('x')){
            size+=1;
        }
        int[] answer = new int[size];
        for(int i = 0; i < arr.length; i++){
            answer[i]=arr[i].length();
        }
        return answer;
    }
}

0 떼기

class Solution {
    public String solution(String n_str) {
        String answer = "";
        boolean startZero = false;
        if(n_str.charAt(0)=='0'){
            startZero=true;
        }
        for(int i = 0; i < n_str.length(); i++){
            if(startZero){
                if(n_str.charAt(i)=='0'){
                    
                }else{
                    answer+=n_str.charAt(i);
                    startZero=false;
                }
            }else{
                answer+=n_str.charAt(i);
            }
        }
        return answer;
    }
}

부분 문자열인지 확인하기

class Solution {
    public int solution(String my_string, String target) {
        int answer = 0;
        if(my_string.contains(target)){
            answer = 1;
        }
        return answer;
    }
}