Sudo Placement | Range Queries

// C# program to find the numbers
// having atmost 3 set bits within
// a given range

using System;
using System.Collections.Generic;

// Class to store the L and R range of a query
public class Query {
    public long L;
    public long R;
}

public class RangeQueries {

    // It returns index of first element which is greater
    // than searched value If searched element is bigger
    // than any array element function returns first index
    // after last element.
    public static int upperBound(List<long> validNumbers,
                                 long value)
    {
        int low = 0;
        int high = validNumbers.Count - 1;

        while (low < high) {
            int mid = (low + high) / 2;
            if (value >= validNumbers[mid]) {
                low = mid + 1;
            }
            else {
                high = mid;
            }
        }
        return low;
    }

    public static void answerQueries(List<Query> queries)
    {
        // Set of Numbers having at most 3 set bits
        // arranged in non-descending order
        HashSet<long> allNum = new HashSet<long>();

        // 0 Set bits
        allNum.Add(0L);

        // Iterate over all possible combinations of i, j, k
        // for
        // 60 bits. And add all the numbers with 0, 1 or 2
        // set bits into the set allNum.
        for (int i = 0; i <= 60; i++) {
            for (int j = 0; j <= 60; j++) {
                for (int k = 0; k <= 60; k++) {

                    // For one set bit, check if i, j, k are
                    // equal if yes, then set that bit and
                    // add it to the set
                    if (i == j && j == k) {
                        allNum.Add(1L << i);
                    }

                    // For two set bits, two of the three
                    // variable i,j,k will be equal and the
                    // third will not be. Set both the bits
                    // where two variables are equal and the
                    // bit which is not equal, and add it to
                    // the set
                    else if (i == j && j != k) {
                        long toAdd = (1L << i) + (1L << k);
                        allNum.Add(toAdd);
                    }
                    else if (i == k && k != j) {
                        long toAdd = (1L << i) + (1L << j);
                        allNum.Add(toAdd);
                    }
                    else if (j == k && k != i) {
                        long toAdd = (1L << j) + (1L << i);
                        allNum.Add(toAdd);
                    }

                    // Setting all the 3 bits
                    else {
                        long toAdd = (1L << i) + (1L << j)
                                     + (1L << k);
                        allNum.Add(toAdd);
                    }
                }
            }
        }

        // Adding all the numbers to an array list so that
        // it can be sorted
        List<long> validNumbers = new List<long>();
        foreach(long num in allNum)
        {
            validNumbers.Add(num);
        }

        validNumbers.Sort();

        // Answer queries by applying binary search
        for (int i = 0; i < queries.Count; i++) {
            long L = queries[i].L;
            long R = queries[i].R;

            // Swap L and R if R is smaller than L
            if (R < L) {
                long temp = L;
                L = R;
                R = temp;
            }

            if (L == 0) {
                int indxOfLastNum
                    = upperBound(validNumbers, R);
                Console.WriteLine(indxOfLastNum + 1);
            }
            else {
                int indxOfFirstNum
                    = upperBound(validNumbers, L);
                int indxOfLastNum
                    = upperBound(validNumbers, R);
                Console.WriteLine(
                    (indxOfLastNum - indxOfFirstNum + 1));
            }
        }
    }

    // Driver code
    public static void Main(string[] args)
    {
        List<Query> queries = new List<Query>();

        Query q1 = new Query();
        q1.L = 3;
        q1.R = 7;

        Query q2 = new Query();
        q2.L = 10;
        q2.R = 16;

        queries.Add(q1);
        queries.Add(q2);

        // Function call
        answerQueries(queries);
    }
}

// This code is contributed by phasing.