21.07.02 [백준] 1920 수 찾기

[blossun]

• 문제

아이디어

• 이분탐색 → 참고 [탐색] #254

어려운점 & 실수

정답

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.StringTokenizer;

public class N1920 {
 public static void main(String[] args) throws IOException {
 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 int N = Integer.parseInt(br.readLine());
 int[] arr = new int[N];
 StringTokenizer stringTokenizer = new StringTokenizer(br.readLine().trim(), " ");
 for (int i = 0; i < N; i++) {
 arr[i] = Integer.parseInt(stringTokenizer.nextToken());
 }
 Arrays.sort(arr);

 int M = Integer.parseInt(br.readLine());
 int[] targets = new int[M];
 int[] answer = new int[M];
 stringTokenizer = new StringTokenizer(br.readLine().trim(), " ");
 for (int i = 0; i < M; i++) {
 targets[i] = Integer.parseInt(stringTokenizer.nextToken());
 }
 for (int i = 0; i < M; i++) {
 int target = targets[i];
 int st = 0;
 int en = N - 1;
 while (st <= en) {
 int mid = (st + en) / 2;
 if (arr[mid] < target) {
 st = mid + 1;
 } else if (arr[mid] > target) {
 en = mid - 1;
 } else {
 answer[i] = 1;
 break;
 }
 }
 }

 StringBuilder sb = new StringBuilder();
 Arrays.stream(answer).forEach(n -> sb.append(n).append('\n'));
 System.out.println(sb.toString());
 }
}