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??????????

2019???????

???????????????????????????????????????????????????????25?????????????????????????7????????????????????????????

Java????????

?2019???????

???????????????????????????????????????????????????????????????

System.out.println(Integer.toBinaryString(2019));

??????????????????????????

????????

System.out.println(Integer.valueOf("11111100011", 2)); // ???????
System.out.println(Integer.valueOf("876", 8));     // ???????
System.out.println(Integer.valueOf("FFFF", 16));   // ????????

????????????

System.out.println(Integer.toOctalString(876)); // ???????
System.out.println(Integer.toHexString(65535)); // ????????

????1200000??????????

????1200000??????????????????????????

int count = 0;
for (int i = 1; i <= Math.sqrt(1200000); i++) {
    if ((1200000 / i) * i == 1200000) {
        count++;
    }
}
System.out.println(count * 2);

????????1??1200000??????????????1200000??????????????????????????????????????????????2?

????2019????????????????

???????????????????????????????????????????????2018???

????

????1-2019??9????????

????1?2019??9??????????????????????????

public class Main {
    public static void main(String[] args) {
        int count = 0;
        for (int i = 0; i <= 2019; i++) {
            if (check(i)) {
                count++;
            }
        }
        System.out.println(count);
    }
    public static boolean check(int n) {
        while (n > 0) {
            if (n % 10 == 9) {
                return true;
            }
            n /= 10;
        }
        return false;
    }
}

????

??????????????????????

??????????????????????????????????????

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String str = scan.nextLine();
        int count = 0;
        for (int i = 0; i < str.length(); i++) {
            char c = str.charAt(i);
            if (isVowelOrConsonant(c)) {
                count++;
            }
        }
        System.out.println(count);
    }
    private static boolean isVowelOrConsonant(char c) {
        c = Character.toLowerCase(c);
        if (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u') {
            return true;
        }
        if (c >= 'a' && c <= 'z') {
            return true;
        }
        return false;
    }
}

????

?????n?????????????m??????????????????

?????????????????????????????

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        int m = scan.nextInt();
        int count = 0;
        int[] numbers = new int[n];
        for (int i = 0; i < n; i++) {
            numbers[i] = scan.nextInt();
        }
        for (int i = 0; i < n; i++) {
            for (int j = n - 1; j >= i; j--) {
                if ((numbers[i] + numbers[j]) % m == 0) {
                    count++;
                }
            }
        }
        System.out.println(count);
    }
}

????

??????1~n????????????????????

????1?n??????????????????????????????????????

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int count = 0;
        int n = scan.nextInt();
        for (int i = 1; i <= n; i++) {
            if (check(i)) {
                count++;
            }
        }
        System.out.println(count);
    }
    private static boolean check(int a) {
        int[] array = new int[10];
        while (a > 0) {
            array[a % 10]++;
            a /= 10;
        }
        for (int j = 0; j < 10; j++) {
            if (array[j] > 1) {
                return false;
            }
        }
        return true;
    }
}

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??????????????????????????(1,1)??(m,n)????????d?????????

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?????????????????????????????????

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        int m = scan.nextInt();
        int[][] a = new int[n][m];
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                a[i][j] = scan.nextInt();
            }
        }
        int[] sum = new int[m];
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                sum[j] += a[i][j];
            }
        }
        int x = sum[0];
        int y = sum[m - 1];
        for (int k = m - 2; k >= 0; k--) {
            for (int r = 1; r <= k; r++) {
                if (x < y) {
                    x += sum[r];
                } else {
                    break;
                }
                if (r == k) {
                    break;
                }
            }
            if (y > x && r + 1 > k) {
                System.out.println(y - x);
                break;
            }
            if (y > x && r == k) {
                break;
            }
        }
        if (x > y) {
            System.out.println(x - y);
        }
    }
}

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