[JAVA] 백준 11663번- 선분 위의 점

https://www.acmicpc.net/problem/11663

11663번: 선분 위의 점

 

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

public class Main {

    static int[] arr;

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        StringTokenizer st = new StringTokenizer(br.readLine());
        int n = Integer.parseInt(st.nextToken());
        int m = Integer.parseInt(st.nextToken());

        arr = new int[n];
        st = new StringTokenizer(br.readLine());

        for (int i = 0; i < n; i++) {
            arr[i] = Integer.parseInt(st.nextToken());
        }

        Arrays.sort(arr);
        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < m; i++) {
            st = new StringTokenizer(br.readLine());
            int start = Integer.parseInt(st.nextToken());
            int end = Integer.parseInt(st.nextToken());

            sb.append(upperBound(end) - lowerBound(start)).append("\n");
        }
        System.out.println(sb);
    }

    static int upperBound(int x) {
        int start = 0;
        int end = arr.length - 1;

        while (start <= end) {
            int mid = (start + end) / 2;
            if (arr[mid] > x) end = mid - 1;
            else start = mid + 1;
        }
        return start;
    }

    static int lowerBound(int x) {
        int start = 0;
        int end = arr.length - 1;

        while (start <= end) {
            int mid = (start + end) / 2;
            if (arr[mid] >= x) end = mid - 1;
            else start = mid + 1;
        }
        return start;
    }

}