0907携程笔试AK代码

Q1

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class P1 {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        List<List<Integer>> lists = new ArrayList<>();
        backtrack(lists, new boolean[n], new ArrayList<>());
        int ans = 0;
        for (List<Integer> list : lists) ans += check(list) ? 1 : 0;
        System.out.println(ans);
    }

    public static void backtrack(List<List<Integer>> lists, boolean[] used, List<Integer> list) {
        if (list.size() == used.length) lists.add(new ArrayList<>(list));
        else {
            for (int i = 1; i <= used.length; i++) {
                if (used[i - 1]) continue;
                list.add(i);
                used[i - 1] = true;
                backtrack(lists, used, list);
                list.remove(list.size() - 1);
                used[i - 1] = false;
            }
        }
    }

    public static boolean check(List<Integer> list) {
        for (int i = 1; i < list.size(); i++) {
            int sum = list.get(i) + list.get(i - 1);
            if (isPrime(sum)) return false;
        }
        return true;
    }

    public static boolean isPrime(int x) {
        if (x == 1 || x % 2 == 0 && x != 2) return false;
        for (int i = 3; i < x; i += 2) {
            if (x % i == 0) return false;
        }
        return true;
    }
}

Q2

import java.util.Scanner;

public class P2 {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt(), m = scan.nextInt();
        char[][] grid = new char[n][], cols = new char[m][3], rows = new char[n][3];
        long ans = 0;
        String you = "you";
        for (int i = 0; i < n; i++) grid[i] = scan.next().toCharArray();
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                int x = you.indexOf(grid[i][j]);
                if (x == -1) continue;
                rows[i][x]++;
                cols[j][x]++;
            }
        }
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                int idx = you.indexOf(grid[i][j]);
                if (idx == -1) continue;
                long[][] array = new long[2][2];
                for (int k = 0, p = 0; k < 3; k++) {
                    if (k != idx) {
                        array[p][0] = rows[i][k];
                        array[p][1] = cols[j][k];
                        p++;
                    }
                }
                ans += array[0][0] * array[1][1] + array[1][0] * array[0][1];
            }
        }
        System.out.println(ans);
    }
}

Q3

import java.util.Scanner;

public class P3 {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int t = scan.nextInt();
        while (t-- > 0) {
            int n = scan.nextInt(), l = scan.nextInt(), r = scan.nextInt();
            int[] array = new int[n];
            long sum = 0, sl = 0, br = 0;
            for (int i = 0; i < n; i++) {
                array[i] = scan.nextInt();
                sum += array[i];
                if (array[i] < l) sl += (l - array[i]);
                else if (array[i] > r) br += (array[i] - r);
            }
            double avg = (double) sum / n;
            if (avg > r || avg < l) System.out.println(-1);
            else System.out.println(Math.max(sl, br));
        }
    }
}

Q4

import java.util.*;

public class P4 {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        char[] cs = scan.next().toCharArray();
        int cnt = 0;
        long ans = 0;
        for (char c : cs) {
            cnt += c == '0' ? 1 : -1;
            if (cnt > 0) ans += cnt;
            else cnt = 0;
        }
        System.out.println(ans);
    }
}