[atcode abc349] D - Divide Interval

• 解决方法，贪心。

import java.io.*;
import java.math.BigInteger;
import java.util.*;

public class Main {
    public static void main(String[] args) throws IOException {
        long L, R;
        L = rd.nextLong();
        R = rd.nextLong();

        PrintWriter out = new PrintWriter(System.out);
        List<long[]> ans = new ArrayList<>();
        if (L == 0) {
            ans.add(new long[]{0,1L << max2(R)});
            L = (1L<<max2(R));
        }
        long curr = L;

        while (curr < R) {
            int h = maxHighBit(curr);
            long diff = R - curr;

            long next = 0;
            if (max2(diff) >= h) {
                next = curr + (1L << h);
            } else {
                next = curr + (1L << max2(diff));
            }
            ans.add(new long[]{curr,next});
            curr = next;
        }
        out.println(ans.size());
        for (long[] tmp:ans) {
            out.println(tmp[0] + " " + tmp[1]);
        }
        out.flush();
        out.close();
    }

    public static int max2(long n) {
        for (int i = 0; i <= 61; i++) {
            if( (1L<<i)  > n) {
                return i - 1;
            }
        }
        return 0;
    }

    public static int maxHighBit(long n) {
        int num = 0;
        while (n % 2 == 0) {
            num++;
            n = n / 2;
        }
        return num;
    }
}

class rd {
    static BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
    static StringTokenizer tokenizer = new StringTokenizer("");

    // nextLine()读取字符串
    static String nextLine() throws IOException {
        return reader.readLine();
    }

    // next()读取字符串
    static String next() throws IOException {
        while (!tokenizer.hasMoreTokens()) tokenizer = new StringTokenizer(reader.readLine());
        return tokenizer.nextToken();
    }

    // 读取一个int型数值
    static int nextInt() throws IOException {
        return Integer.parseInt(next());
    }

    // 读取一个double型数值
    static double nextDouble() throws IOException {
        return Double.parseDouble(next());
    }

    // 读取一个long型数值
    static long nextLong() throws IOException {
        return Long.parseLong(next());
    }

    // 读取一个BigInteger
    static BigInteger nextBigInteger() throws IOException {
        BigInteger d = new BigInteger(rd.nextLine());
        return d;
    }
}