[2주차] #10

Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,24 @@
	import java.util.*;

	class Solution {
	public String solution(String[] participant, String[] completion) {
	String answer = "";
	Map<String, Integer> map = new HashMap<>();

	for(String str : participant){
	map.put(str, map.getOrDefault(str, 0)+1);
	}

	for(String str : completion){
	map.put(str, map.get(str)-1);
	}

	for(String key : map.keySet()){
	if(map.get(key) == 1){
	answer = key;
	}
	}

	return answer;
	}
	}

33 changes: 33 additions & 0 deletions EunjiShin/PS/programmers/해시/전화번호 목록.java

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Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,33 @@
	import java.util.*;

	class Solution {
	public boolean solution(String[] phone_book) {
	boolean answer = true;
	Map<String, String> map = new HashMap<>();

	Arrays.sort(phone_book);
	for(String phone_number : phone_book){
	map.put(phone_number, "1");
	}

	for(String phone_number : phone_book){
	for(int i=0; i<phone_number.length(); i++){
	String str = phone_number.substring(0, i);
	if(map.containsKey(str)){
	return false;
	}
	}
	}

	// Hash없이 푼다면 startsWith
	// Arrays.sort(phone_book);
	// for (int i=0; i<phone_book.length-1; i++) {
	// if (phone_book[i+1].startsWith(phone_book[i])) {
	// answer = false;
	// break;
	// }
	// }

	return answer;
	}
	}

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