Donat un nombre n, imprimeix els primers n nombres enters positius amb exactament dos bits establerts en la seva representació binària.
Exemples:
Input: n = 3
Output: 3 5 6
The first 3 numbers with two set bits are 3 (0011)
5 (0101) and 6 (0110)
Input: n = 5
Output: 3 5 6 9 10 12
A Solució senzilla és considerar tots els nombres enters positius un per un a partir de l'1. Per a cada nombre comproveu si té exactament dos conjunts de bits. Si un nombre té exactament dos bits establerts, imprimiu-lo i augmenteu el recompte d'aquests nombres.
An Solució eficient és generar directament aquests números. Si observem clarament els nombres, els podem reescriure com es mostra a continuació pow(21)+pow(20) pow(22)+pow(20) pow(22)+pow(21) pow(23)+pow(20) pow(23)+pow(21) pow(23)+pow(22) .........
Tots els números es poden generar en ordre creixent segons el més alt dels dos bits establerts. La idea és arreglar més alt de dos bits un per un. Per al bit de conjunt més alt actual, considereu tots els bits inferiors i imprimiu els números formats.
C++
// C++ program to print first n numbers // with exactly two set bits #include
// Java program to print first n numbers // with exactly two set bits import java.io.*; class GFG { // Function to print first n numbers with two set bits static void printTwoSetBitNums(int n) { // Initialize higher of two sets bits int x = 1; // Keep reducing n for every number // with two set bits while (n > 0) { // Consider all lower set bits for // current higher set bit int y = 0; while (y < x) { // Print current number System.out.print(((1 << x) + (1 << y)) +' '); // If we have found n numbers n--; if (n == 0) return; // Consider next lower bit for current // higher bit. y++; } // Increment higher set bit x++; } } // Driver program public static void main (String[] args) { int n = 4; printTwoSetBitNums(n); } } // This code is contributed by Pramod Kumar
# Python3 program to print first n # numbers with exactly two set bits # Prints first n numbers # with two set bits def printTwoSetBitNums(n) : # Initialize higher of # two sets bits x = 1 # Keep reducing n for every # number with two set bits. while (n > 0) : # Consider all lower set bits # for current higher set bit y = 0 while (y < x) : # Print current number print((1 << x) + (1 << y) end = ' ' ) # If we have found n numbers n -= 1 if (n == 0) : return # Consider next lower bit # for current higher bit. y += 1 # Increment higher set bit x += 1 # Driver code printTwoSetBitNums(4) # This code is contributed # by Smitha
// C# program to print first n numbers // with exactly two set bits using System; class GFG { // Function to print first n // numbers with two set bits static void printTwoSetBitNums(int n) { // Initialize higher of // two sets bits int x = 1; // Keep reducing n for every // number with two set bits while (n > 0) { // Consider all lower set bits // for current higher set bit int y = 0; while (y < x) { // Print current number Console.Write(((1 << x) + (1 << y)) +' '); // If we have found n numbers n--; if (n == 0) return; // Consider next lower bit // for current higher bit. y++; } // Increment higher set bit x++; } } // Driver program public static void Main() { int n = 4; printTwoSetBitNums(n); } } // This code is contributed by Anant Agarwal.
<script> // Javascript program to print first n numbers // with exactly two set bits // Prints first n numbers with two set bits function printTwoSetBitNums(n) { // Initialize higher of two sets bits let x = 1; // Keep reducing n for every number // with two set bits. while (n > 0) { // Consider all lower set bits for // current higher set bit let y = 0; while (y < x) { // Print current number document.write((1 << x) + (1 << y) + ' '); // If we have found n numbers n--; if (n == 0) return; // Consider next lower bit for current // higher bit. y++; } // Increment higher set bit x++; } } // Driver code printTwoSetBitNums(4); // This code is contributed by Mayank Tyagi </script>
// PHP program to print // first n numbers with // exactly two set bits // Prints first n numbers // with two set bits function printTwoSetBitNums($n) { // Initialize higher of // two sets bits $x = 1; // Keep reducing n for // every number with // two set bits. while ($n > 0) { // Consider all lower set // bits for current higher // set bit $y = 0; while ($y < $x) { // Print current number echo (1 << $x) + (1 << $y) ' '; // If we have found n numbers $n--; if ($n == 0) return; // Consider next lower // bit for current // higher bit. $y++; } // Increment higher set bit $x++; } } // Driver code printTwoSetBitNums(4); // This code is contributed by Ajit ?> Sortida:
java do while bucle
3 5 6 9
Complexitat temporal: O(n)
inserir al teclat
Espai auxiliar: O(1)
Enfocament núm. 2: utilitzar while i join
L'enfocament és començar des de l'enter 3 i comprovar si el nombre de bits establerts en la seva representació binària és igual a 2 o no. Si té exactament 2 bits establerts, afegiu-lo a la llista de números amb 2 bits establerts fins que la llista tingui n elements.
Algorisme
1. Inicialitzeu una llista buida res per emmagatzemar els nombres enters amb exactament dos bits establerts.
2. Inicialitzeu una variable entera i a 3.
3. Si bé la longitud de la llista res és menor que n, feu el següent:
a. Comproveu si el nombre de bits establerts a la representació binària de i és igual a 2 o no utilitzant el mètode count() de la cadena.
b. Si el nombre de bits establerts és igual a 2, afegiu i a la llista res.
c. Incrementa i en 1.
4. Retorna la llista res.
#include
// Java program for the above approach import java.util.ArrayList; import java.util.List; public class GFG { // Function to count the number of set bits (binary 1s) // in an integer static int countSetBits(int num) { int count = 0; while (num > 0) { count += num & 1; // Increment count if the last // bit is set (1) num >>= 1; // Right shift to check the next bit } return count; } // Function to generate 'n' numbers with exactly two set // bits in their binary representation static List<Integer> numbersWithTwoSetBits(int n) { List<Integer> res = new ArrayList<>(); int i = 3; // Start from 3 as the first number with // two set bits while (res.size() < n) { if (countSetBits(i) == 2) { // Check if the number has exactly // two set bits res.add( i); // Add the number to the result list } i++; // Move to the next number } return res; } public static void main(String[] args) { int n = 3; // Number of numbers with two set bits to // generate List<Integer> result = numbersWithTwoSetBits( n); // Get the generated numbers for (int num : result) { System.out.print( num + ' '); // Display the generated numbers } System.out.println(); } } // This code is contributed by Susobhan Akhuli
def numbersWithTwoSetBits(n): res = [] i = 3 while len(res) < n: if bin(i).count('1') == 2: res.append(i) i += 1 return res n = 3 result = numbersWithTwoSetBits(n) output_string = ' '.join(str(x) for x in result) print(output_string)
using System; using System.Collections.Generic; class Program { // Function to count the number of set bits (binary 1s) in an integer static int CountSetBits(int num) { int count = 0; while (num > 0) { count += num & 1; // Increment count if the last bit is set (1) num >>= 1; // Right shift to check the next bit } return count; } // Function to generate 'n' numbers with exactly two set bits in their binary representation static List<int> NumbersWithTwoSetBits(int n) { List<int> res = new List<int>(); int i = 3; // Start from 3 as the first number with two set bits while (res.Count < n) { if (CountSetBits(i) == 2) // Check if the number has exactly two set bits { res.Add(i); // Add the number to the result list } i++; // Move to the next number } return res; } static void Main(string[] args) { int n = 3; // Number of numbers with two set bits to generate List<int> result = NumbersWithTwoSetBits(n); // Get the generated numbers Console.Write('Result: '); foreach (int num in result) { Console.Write(num + ' '); // Display the generated numbers } Console.WriteLine(); } }
// Javascript program for the above approach // Function to count the number of set bits (binary 1s) // in an integer function countSetBits(num) { let count = 0; while (num > 0) { count += num & 1; // Increment count if the last // bit is set (1) num >>= 1; // Right shift to check the next bit } return count; } // Function to generate 'n' numbers with exactly two set // bits in their binary representation function numbersWithTwoSetBits(n) { let res = []; let i = 3; // Start from 3 as the first number with // two set bits while (res.length < n) { if (countSetBits(i) === 2) { // Check if the number has exactly // two set bits res.push(i); // Add the number to the result list } i++; // Move to the next number } return res; } // Number of numbers with two set bits to generate let n = 3; // Get the generated numbers let result = numbersWithTwoSetBits(n); // Display the generated numbers console.log(result.join(' ')); // This code is contributed by Susobhan Akhuli
Sortida
3 5 6
Complexitat temporal: O(n log n) on n és el nombre de nombres enters amb exactament dos bits establerts. Això es deu al fet que estem comprovant el nombre de bits establerts en la representació binària de cada nombre enter que triga O(log n) temps.
torna a tornar la closca
Complexitat espacial: O(n) on n és el nombre d'enters amb exactament dos bits establerts. Això és perquè estem emmagatzemant la llista de nombres enters amb dos bits establerts a la memòria.