A

(long)sqrt(N) * 2 + 1

B

N / 100 * 2

什么环来着

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();
        String[] s = new String[n + 1];
        int[][] g = new int[n + 1][n + 1];

        for(int i = 1; i <= n; i++){
            s[i] = scan.next();
            s[i] = s[i] + s[i];
        }

        // 构建完整的带权图
        for(int i = 1; i <= n; i++){
            for(int j = i + 1; j <= n; j++){
                g[i][j] = g[j][i] = Math.min(m, work(s[i], s[j])); 
            }
        }

        // 使用Prim算法找到最大权值的最小生成树
        int[] mx = new int[n + 1];
        boolean[] st = new boolean[n + 1];
        Arrays.fill(mx, Integer.MIN_VALUE); 
        mx[1] = 0;

        int res = 0;

        for(int i = 1; i <= n; i++){
            int idx = -1;
            for(int j = 1; j <= n; j++){
                if(!st[j] && (idx == -1 || mx[j] > mx[idx])){
                    idx = j;
                }
            }

            st[idx] = true;
            res += mx[idx];

            for(int j = 1; j <= n; j++){
                if(!st[j] && g[idx][j] > mx[j]){
                    mx[j] = g[idx][j];
                }
            }
        }

        System.out.println(res);
    }

    public static int work(String s1, String s2) {
        int m = s1.length();
        int n = s2.length();

        int[][] dp = new int[m + 1][n + 1];
        int maxLength = 0;

        for (int i = 1; i <= m; i++) {
            for (int j = 1; j <= n; j++) {
                if (s1.charAt(i - 1) == s2.charAt(j - 1)) {
                    dp[i][j] = dp[i - 1][j - 1] + 1;
                    if (dp[i][j] > maxLength) {
                        maxLength = dp[i][j];
                    }
                } else {
                    dp[i][j] = 0;
                }
            }
        }
        return maxLength;
    }
}

博弈

import java.util.*;

public class Main{

    static int N = (int) 1e5 + 10;
    static int[] prime = new int[N];
    static int cnt = 0;
    static boolean[] st = new boolean[N];
    static int[] res = new int[N];

    static void init(){
        for(int i = 2; i < N; i++){
            if(!st[i]) prime[cnt++] = i;
            for(int j = 0; j < cnt && prime[j] * i < N; j++){
                st[prime[j] * i] = true;
            }
        }

        for(int i = 0; i < cnt; i++){
            res[prime[i]] = res[prime[i] + 1] = 1;
        }

        for(int i = 2; i < N; i++){
            for(int j = 0; j < cnt && prime[j] <= i; j++){
                if(res[i - prime[j]] == 0) {
                    res[i] = 1;
                    break;
                }
            }
        }

        // for(int i = 0; i < 100; i++){
        //     System.out.print(res[i] + " ");
        // }
    }

    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        init();
        int q = scan.nextInt();
        for(int i = 0; i < q; i++){
            int n = scan.nextInt();
            System.out.println(res[n]);
        }
    }
}

删什么玩意来着

import java.util.*;

public class Main{

    static boolean check(long a){
        long l = 1, r = (long) 1e9;
        while(l <= r){
            long mid = l + r >> 1;
            long sum = 0;
            if(mid % 2 == 0){
                sum = (1 + mid) * (mid / 2);
            }else{
                sum = (1 + mid) * (mid / 2) + (mid + 1) / 2;
            }

            if(sum == a){
                return true;
            }else if(sum > a){
                r = mid - 1;
            }else{
                l = mid + 1;
            }
        }
        return false;
    }

    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        int res = 0;
        for(int i = 0; i < n; i++){
            long a = scan.nextLong();
            if(!check(a)){
                res++;
            }
        }
        System.out.println(res);
    }
}

什么回文数操作

import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        int[] a = new int[n];
        long[] b = new long[n];
        for(int i = 0; i < n; i++){
            a[i] = scan.nextInt();
        }
        for(int i = 0, j = n - 1; i < j; i++, j--){
            b[i] = a[j] - a[i];
        }
        long res = 0;
        for(int i = 0; i < n / 2; i++){
            res += Math.abs(b[i]);
            if(b[i] * b[i + 1] > 0){
                if(b[i] > 0) {
                    b[i + 1] = Math.max(0L, b[i + 1] - b[i]);
                }else{
                    b[i + 1] = Math.min(0L, b[i + 1] - b[i]);
                }
            }
        }
        System.out.println(res);
    }
}

最后一题太难了，没看，还有一道题忘了题目了，写7个小菜