Question 1. Find # of elements smaller than max value

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    static int birthdayCakeCandles(int n, int[] ar) {
        int max = Arrays.stream(ar).max().getAsInt();
        return (int)Arrays.stream(ar).filter(i -> i == max).count();
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[] ar = new int[n];
        for(int ar_i = 0; ar_i < n; ar_i++){
            ar[ar_i] = in.nextInt();
        }
        int result = birthdayCakeCandles(n, ar);
        System.out.println(result);
    }
}

Question 2. Count apples and orange

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int s = in.nextInt();
        int t = in.nextInt();
        int a = in.nextInt();
        int b = in.nextInt();
        int m = in.nextInt();
        int n = in.nextInt();

        int[] apple = new int[m];
        for(int apple_i=0; apple_i < m; apple_i++){
            apple[apple_i] = in.nextInt();
        }
        int[] orange = new int[n];
        for(int orange_i=0; orange_i < n; orange_i++){
            orange[orange_i] = in.nextInt();
        }

        int appleCnt = (int) Arrays.stream(apple).filter(x-> x + a >= s && x+a<=t).count();
        int orageCnt = (int) Arrays.stream(orange).filter(x-> x + b >= s && x+b<=t).count();;

        System.out.println(appleCnt +"\n"+orageCnt);     
    }
}

Question 3. Count camel case

• count every words in the sentence (e.g. saveToStreamObjects -> save, To, Stream,Objects -> 4)

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String s = in.next();
        // convert String to Stream, use mapToObj function.        
        System.out.println(s.chars().mapToObj(ch -> Character.valueOf((char)ch)).filter(x-> x>='A' && x <= 'Z').count()+1);
    }
}