[알고리즘문제풀기] 문자열 섞기

문제

내가 작성한 정답

String

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

StringBuilder, StringBuffer

class Solution {
    public String solution(String str1, String str2) {
        StringBuilder answer = new StringBuilder();
        // StringBuffer answer = new StringBuffer();
        for(int i=0;i<str1.length(); i++){
            answer.append(str1.charAt(i));
            answer.append(str2.charAt(i));
        }
        return answer.toString();
    }
}

StringBuilder, StringBuffer - String[], char[]

class Solution {
    public String solution(String str1, String str2) {
        StringBuilder answer = new StringBuilder();
        // StringBuffer answer = new StringBuffer();
        String[] str11 = str1.split("");
        String[] str22 = str2.split("");
        // char[] str11 = str1.toCharArray();
        // char[] str22 = str2.toCharArray();
        for(int i=0;i<str1.length(); i++){
            answer.append(str11[i]);
            answer.append(str22[i]);
        }
        return answer.toString();
    }
}

Stream

import java.util.stream.IntStream;

class Solution {
    public String solution(String str1, String str2) {
        return IntStream.range(0,str2.length())
                .mapToObj(i-> String.valueOf(str1.charAt(i))+String.valueOf(str2.charAt(i)))
                // .reduce("",String::concat);
                // .reduce("",(a,b)->a+b);                
                 .collect(Collectors.joining());
    }
}
// reduce - 스트림의 요소를 결합하여 단일 결과값을 생성
// reduce(초기값, 스트림 누적 함수)

다른 사람들의 정답

StringBuilder에서 append 연속으로 사용가능하다!

class Solution {
    public String solution(String str1, String str2) {
        char[] chars1 = str1.toCharArray();
        char[] chars2 = str2.toCharArray();

        StringBuilder sb = new StringBuilder();
        for (int i=0; i<chars1.length; i++) {
            sb.append(chars1[i]).append(chars2[i]);
        }

        return sb.toString();
    }
}

charAt으로 연속으로 더하기

class Solution {
    public String solution(String str1, String str2) {
        String answer = "";

        for(int i=0; i<str1.length(); i++) {
            answer += "" + str1.charAt(i) + str2.charAt(i);
        }

        return answer;
    }
}