腾讯笔试题解

// 第一题 最小公倍数
public class Main {

    public static void main(String[] args) throws Exception {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        getPrime(n);
        long ans = 2;
        for (int i = 0; i < cnt; i++) {
            int p = prime[i];
            long a = 1;
            while (a * p <= n) {
                a *= p;
            }
            long b = (n / a + 1) * a;
            ans = Math.max(b, ans);
        }
        System.out.println(ans);
    }

    static int cnt = 0, N = 1000006;
    static boolean[] tag = new boolean[N];
    static int[] prime = new int[N];

    private static void getPrime(int maxnum) {
        tag[0] = tag[1] = true;
        int i, j;
        for (i = 2; i <= maxnum; i++) {
            if (tag[i] == false) {
                prime[cnt++]=i;
                for(j = i + i; j <= maxnum; j += i)
                {
                    tag[j] = true;
                }
            }
        }
    }
}

// 第二题 重要城市
public class Main2 {

    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String str = br.readLine();
        String[] ss = str.split(" ");
        int n = Integer.parseInt(ss[0]), m = Integer.parseInt(ss[1]);
        boolean[][] nodes = new boolean[n+1][n+1];
        for (int i = 0; i < m; i++) {
            String[] tt = br.readLine().split(" ");
            int a = Integer.parseInt(tt[0]);
            int b = Integer.parseInt(tt[1]);
            nodes[a][b] = true;
        }
        int[] nums = new int[n+1];
        for (int i = 1; i <= n; i++) {
            boolean[] vis = new boolean[n+1];
            dfs(nodes, i, i, nums, vis);
        }
        int cnt = 0;
        for (int i = 0; i < nums.length; i++) {
            if (nums[i] > 0) {
                cnt++;
            }
        }
        System.out.println(cnt);
    }

    private static void dfs(boolean[][] nodes, int idx,int tar, int[] nums, boolean[] vis) {
        for (int i = 1; i < nodes.length; i++) {
            if (i != idx && nodes[idx][i] && !vis[i]) {
                nums[tar]--;
                nums[i]++;
                vis[i] = true;
                dfs(nodes, i, tar, nums, vis);
            }
        }
    }
}

// 第三题 Yes No
public class Main3 {

    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String str = br.readLine();
        int n = Integer.parseInt(str);

        for (int i = 0; i < n; i++) {
            String line = br.readLine();
            String[] ss = line.split(" ");
            int a = Integer.parseInt(ss[0]);
            int b = Integer.parseInt(ss[1]);
            int c = Integer.parseInt(ss[2]);
            int mod = a % b;
            Set<Integer> set = new HashSet<>();
            set.add(mod);
            while (mod != c) {
                mod = (mod + a) % b;
                if (set.contains(mod)) break;
            }
            System.out.println(mod == c ? "YES" : "NO");
        }
    }
}