[기초][JAVA][02.13] 프로그래머스 코딩테스트

문자열 붙여서 출력하기

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

flag에 따라 다른 값 반환하기

class Solution {
    public int solution(int a, int b, boolean flag) {
        int answer = 0;
        if(flag == true){
            answer = a + b;
        }else{answer = a - b;}
        return answer;
    }
}

공배수

class Solution {
    public int solution(int number, int n, int m) {
        int answer = (number%n==0)&&(number%m==0) ? 1 : 0;
        return answer;
    }
}

문자열을 정수로 변환하기

class Solution {
    public int solution(String n_str) {
        int answer = Integer.parseInt(n_str);
        return answer;
    }
}

문자열 정수의 합

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

정수 부분

class Solution {
    public int solution(double flo) {
        int answer = (int)flo;
        return answer;
    }
}

뒤에서 5등까지

import java.util.*;

class Solution {
    public int[] solution(int[] num_list) {
        int[] answer = new int[5];
        Arrays.sort(num_list);
        for(int i = 0; i<5; i++){
            answer[i] = num_list[i];
        }
        return answer;
    }
}

배열의 길이에 따라 다른 연산하기

class Solution {
    public int[] solution(int[] arr, int n) {
        int[] answer = {};
        if(arr.length%2==0){
            for(int j = 1; j<arr.length; j+=2){
                arr[j] += n;
            }
        }else{
            for(int i = 0; i<arr.length; i+=2){
                arr[i] += n;
                System.out.println(i);
            }
        }
        return arr;
    }
}

배열 비교하기

class Solution {
    public int solution(int[] arr1, int[] arr2) {
        int answer = 0;
        int sum1 = 0;
        int sum2 = 0;
        if(arr1.length<arr2.length){
            answer = -1;
        }else if(arr1.length>arr2.length){
            answer = 1;
        }else{
            
            for(int i = 0; i < arr1.length; i++){
                sum1+=arr1[i];
                sum2+=arr2[i];
            }
            if(sum1<sum2){
                answer = -1;
            }else if(sum1 > sum2){
                answer = 1;
            }else{
                answer = 0;
            }
        }
        return answer;
    }
}

rny_string

class Solution {
    public String solution(String rny_string) {
        StringBuilder string = new StringBuilder();
        
        for(int i = 0; i < rny_string.length(); i++){
            char c = rny_string.charAt(i);
            if(c=='m'){
                string.append("rn");
            }else{
                string.append(c);
            }
        }
        return string.toString();
        
        
    }
}

문자열 바꿔서 찾기

class Solution {
    public int solution(String myString, String pat) {
        int answer = 0;
        StringBuilder sb = new StringBuilder();
        
        for(int i = 0; i<pat.length(); i++){
            char ch = pat.charAt(i);
            if(ch=='B'){
                sb.append('A');    
            }else{
                sb.append('B');
            }
        }
        pat = sb.toString();
        for(int j = 0; j<myString.length()-pat.length()+1; j++){
            if(myString.substring(j, j+pat.length()).equals(pat)){
                answer = 1;
                break;
            }
        }
        System.out.println(myString);
        System.out.println(pat);
        
        return answer;
    }
}

특정한 문자를 대문자로 바꾸기

import java.util.*;

class Solution {
    public String solution(String my_string, String alp) {
        StringBuilder answer = new StringBuilder();
        
        for(int i = 0; i < my_string.length(); i++){
            char ch = my_string.charAt(i);
            if(ch == alp.charAt(0)){
                answer.append(Character.toUpperCase(ch)); 
                System.out.println("같음");
            }else{
                answer.append(ch);
            }
        }
    
        return answer.toString();
    }
}

A 강조하기

class Solution {
    public String solution(String myString) {
        StringBuilder answer = new StringBuilder();
        for(int i = 0; i < myString.length(); i++){
            if(myString.charAt(i)=='a' || myString.charAt(i)=='A'){
                answer.append('A');
            }else{
                answer.append(Character.toLowerCase(myString.charAt(i)));
            }
        }
        return answer.toString();
    }
}

배열에서 문자열 대소문자 변환하기

class Solution {
    public String[] solution(String[] strArr) {
        String[] answer = {};
        for(int i = 0; i < strArr.length; i++){
            if(i%2!=0){
                strArr[i] = strArr[i].toUpperCase();
            }else{
                strArr[i] = strArr[i].toLowerCase();
            }
        }
        return strArr;
    }
}

소문자로 바꾸기

class Solution {
    public String solution(String myString) {
        String answer = myString.toLowerCase();
        return answer;
    }
}

대문자로 바꾸기

class Solution {
    public String solution(String myString) {
        String answer = myString.toUpperCase();
        return answer;
    }
}

원하는 문자열 찾기

class Solution {
    public int solution(String myString, String pat) {
        int answer = 0;
        myString = myString.toLowerCase();
        pat = pat.toLowerCase();
        for(int i = 0; i < myString.length() - pat.length() + 1; i++){
            if(myString.substring(i,i+pat.length()).equals(pat)){
                answer = 1;
            }         
        }
        return answer;
    }
}

길이에 따른 연산

class Solution {
    public int solution(int[] num_list) {
        int answer = num_list[0];
        for(int i = 1; i < num_list.length; i++){
            if(num_list.length>10){
                answer += num_list[i];
            }else{
                answer *= num_list[i];
            }
        }
        return answer;
    }
}

조건에 맞게 수열 변환하기 1

class Solution {
    public int[] solution(int[] arr) {
        int[] answer = new int[arr.length];
        for(int i = 0; i<arr.length; i++){
            if(arr[i]>=50 && arr[i]%2==0){
                answer[i] = arr[i]/2;
            }else if(arr[i]<50 && arr[i]%2!=0){
                answer[i] = arr[i]*2;
            }else{
                answer[i] = arr[i];
            }
        }
        return answer;
    }
}

n보다 커질 때까지 더하기

class Solution {
    public int solution(int[] numbers, int n) {
        int answer = 0;
        for(int i = 0; i < numbers.length; i++){
            if(answer <= n){
                answer += numbers[i];
            }else{
                break;
            }
        }
        return answer;
    }
}

할 일 목록

import java.util.*;

class Solution {
    public String[] solution(String[] todo_list, boolean[] finished) {
        
        ArrayList<String> al = new ArrayList<>();
        for(int i = 0; i < todo_list.length; i++){
            if(finished[i]==false){
                al.add(todo_list[i]);
            }
        }
        String[] answer = al.toArray(new String[0]);
        return answer;
    }
}

5명씩

import java.util.*;

class Solution {
    public String[] solution(String[] names) {
        
        ArrayList<String> al = new ArrayList<>();
        for(int i = 0; i < names.length; i+=5){
            al.add(names[i]);
        }
        String[] answer = al.toArray(new String[0]);
        return answer;
    }
}

홀수 vs 짝수

class Solution {
    public int solution(int[] num_list) {
        int answer = 0;
        int sum1 = 0;
        int sum2 = 0;
        for(int i = 0; i < num_list.length; i++){
            if(i%2==0){
                sum1 += num_list[i];
            }else{
                sum2 += num_list[i];
            }
        }
        if(sum1>sum2){
            answer = sum1;
        }else{
            answer = sum2; 
        }
        return answer;
    }
}

수 조작하기 2

class Solution {
    public String solution(int[] numLog) {
        String answer = "";
        for (int i = 0; i < numLog.length-1; i++){
            if(numLog[i] - numLog[i+1] == -1){
                answer += "w";
            }else if(numLog[i] - numLog[i+1] == 1){
                answer += "s";
            }else if(numLog[i] - numLog[i+1] == -10){
                answer += "d";
            }else if(numLog[i] - numLog[i+1] == 10){
                answer += "a";
            }
        }
        return answer;
    }
}

수 조작하기 1

class Solution {
    public int solution(int n, String control) {
        int answer = n;
        for(int i = 0; i < control.length(); i++){
            String wasd = control.substring(i, i+1);
            if(wasd.equals("w")){
                answer += 1;
            }else if(wasd.equals("s")){
                answer -= 1;
            }else if(wasd.equals("d")){
                answer += 10;
            }else if(wasd.equals("a")){
                answer -= 10;
            }
        }
        return answer;
    }
}

마지막 두 원소

import java.util.*;

class Solution {
    public int[] solution(int[] num_list) {
        int[] answer = new int[num_list.length+1];
        for (int i = 0; i < num_list.length; i++){
            answer[i] = num_list[i];
        }
        answer[answer.length-1] = num_list[num_list.length-1] > num_list[num_list.length-2] ? num_list[num_list.length-1] - num_list[num_list.length-2] : num_list[num_list.length-1]*2;
        return answer;
    }
}

원소들의 곱과 합

class Solution {
    public int solution(int[] num_list) {
        int answer = 0;
        int sum = num_list[0];
        int mul = num_list[0];
        for (int i=1; i < num_list.length; i++){
            sum += num_list[i];
            mul *= num_list[i];
        }
        sum *= sum;
        answer = sum > mul ? 1 : 0;
        return answer;
    }
}

문자 리스트를 문자열로 변환하기

class Solution {
    public String solution(String[] arr) {
        String answer = "";
        for(String idx: arr){
            answer += idx;
        }
        return answer;
    }
}

문자열 돌리기

import java.util.Scanner;

public class Solution {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String a = sc.next();
        for(int i = 0; i < a.length(); i++){
            System.out.println(a.substring(i, i+1));
        }
    }
}

덧셈식 출력하기

import java.util.Scanner;

public class Solution {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();

        System.out.println(a + " + " + b + " = " + (a + b));
    }
}

주사위 게임2

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

두 수의 연산값 비교하기

class Solution {
    public int solution(int a, int b) {
        String ab = String.valueOf(a)+String.valueOf(b);
        int ab2 = 2*a*b;
        int answer = (Integer.valueOf(ab) >= ab2 ? Integer.valueOf(ab) : ab2);
        return answer;
    }
}

문자열 곱하기

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

더 크게 합치기

class Solution {
    public int solution(int a, int b) {
        int answer = 0;
        String ab = String.valueOf(a)+String.valueOf(b);
        String ba = String.valueOf(b)+String.valueOf(a);
        answer = Integer.valueOf(ab)>Integer.valueOf(ba) ? Integer.valueOf(ab) : Integer.valueOf(ba);
        return answer;
    }
}

n의 배수

class Solution {
    public int solution(int num, int n) {
        int answer = num%n==0 ? 1 : 0;
        return answer;
    }
}

홀짝 구분하기

import java.util.Scanner;

public class Solution {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        System.out.println(n % 2 == 0 ? (n + " is even") : (n + " is odd"));
    }
}

이어 붙인 수

class Solution {
    public int solution(int[] num_list) {
        int answer = 0;
        String odd = ""; // 홀수
        String even = ""; // 짝수
        for(int i = 0; i < num_list.length; i++){
            if (num_list[i]%2==0){
                even += String.valueOf(num_list[i]);
            }else{
                odd += String.valueOf(num_list[i]);
            }
        }
        answer = Integer.valueOf(even) + Integer.valueOf(odd);
        return answer;
    }
}

홀짝에 따라 다른 값 반환하기

class Solution {
    public int solution(int n) {
        int answer = 0;
        for (int i = n; i > 0; i-=2){
            if(n%2!=0){
                answer += i;
            }else{
                answer += i*i;
            }
        }
        return answer;
    }
}

공배수

class Solution {
    public int solution(int number, int n, int m) {
        int answer = (number%n==0)&&(number%m==0) ? 1 : 0;
        return answer;
    }
}

등차수열의 특정한 항만 더하기

class Solution {
    public int solution(int a, int d, boolean[] included) {
        int answer = 0;
        int[] result = new int[included.length];
        
        for(int i = 0; i < included.length; i++){
            result[i] = a + (d * i);
            if(included[i]==true){
                answer += result[i];
            }
        }
        return answer;
        }
}

문자열 섞기

class Solution {
    public String solution(String str1, String str2) {
        String answer = "";
        for(int i = 0; i < str1.length(); i++){
            answer += str1.substring(i,i+1);
            answer += str2.substring(i,i+1);
        }
        return answer;
    }
}