Dada una array arr[] de N enteros positivos. La tarea es escribir un programa para encontrar la suma de todos los elementos primos en la array dada.
Ejemplos :
Entrada : arr[] = {1, 3, 4, 5, 7}
Salida : 15
Hay tres primos, 3, 5 y 7 cuya suma =15.
Entrada : arr[] = {1, 2, 3, 4, 5, 6, 7}
Salida : 17
Enfoque ingenuo: una solución simple es atravesar la array y seguir verificando cada elemento si es primo o no y agregar el elemento primo al mismo tiempo.
Enfoque eficiente: genere todos los números primos hasta el elemento máximo de la array utilizando el tamiz de Eratóstenes y guárdelos en un hash. Ahora recorra la array y encuentre la suma de los elementos que son primos usando el tamiz.
A continuación se muestra la implementación del enfoque eficiente:
C++
// CPP program to find sum of // primes in given array. #include <bits/stdc++.h> using namespace std; // Function to find count of prime int primeSum(int arr[], int n) { // Find maximum value in the array int max_val = *max_element(arr, arr + n); // USE SIEVE TO FIND ALL PRIME NUMBERS LESS // THAN OR EQUAL TO max_val // Create a boolean array "prime[0..n]". A // value in prime[i] will finally be false // if i is Not a prime, else true. vector<bool> prime(max_val + 1, true); // Remaining part of SIEVE prime[0] = false; prime[1] = false; for (int p = 2; p * p <= max_val; p++) { // If prime[p] is not changed, then // it is a prime if (prime[p] == true) { // Update all multiples of p for (int i = p * 2; i <= max_val; i += p) prime[i] = false; } } // Sum all primes in arr[] int sum = 0; for (int i = 0; i < n; i++) if (prime[arr[i]]) sum += arr[i]; return sum; } // Driver code int main() { int arr[] = { 1, 2, 3, 4, 5, 6, 7 }; int n = sizeof(arr) / sizeof(arr[0]); cout << primeSum(arr, n); return 0; }
Java
// Java program to find sum of // primes in given array. import java.util.*; class GFG { // Function to find count of prime static int primeSum(int arr[], int n) { // Find maximum value in the array int max_val = Arrays.stream(arr).max().getAsInt(); // USE SIEVE TO FIND ALL PRIME NUMBERS LESS // THAN OR EQUAL TO max_val // Create a boolean array "prime[0..n]". A // value in prime[i] will finally be false // if i is Not a prime, else true. Vector<Boolean> prime = new Vector<>(max_val + 1); for(int i = 0; i < max_val + 1; i++) prime.add(i,Boolean.TRUE); // Remaining part of SIEVE prime.add(0,Boolean.FALSE); prime.add(1,Boolean.FALSE); for (int p = 2; p * p <= max_val; p++) { // If prime[p] is not changed, then // it is a prime if (prime.get(p) == true) { // Update all multiples of p for (int i = p * 2; i <= max_val; i += p) prime.add(i,Boolean.FALSE); } } // Sum all primes in arr[] int sum = 0; for (int i = 0; i < n; i++) if (prime.get(arr[i])) sum += arr[i]; return sum; } // Driver code public static void main(String[] args) { int arr[] = { 1, 2, 3, 4, 5, 6, 7 }; int n = arr.length; System.out.print(primeSum(arr, n)); } } /* This code contributed by PrinciRaj1992 */
Python
# Python3 program to find sum of # primes in given array. # Function to find count of prime def primeSum( arr, n): # Find maximum value in the array max_val = max(arr) # USE SIEVE TO FIND ALL PRIME NUMBERS LESS # THAN OR EQUAL TO max_val # Create a boolean array "prime[0..n]". A # value in prime[i] will finally be False # if i is Not a prime, else true. prime=[True for i in range(max_val + 1)] # Remaining part of SIEVE prime[0] = False prime[1] = False for p in range(2, max_val + 1): if(p * p > max_val): break # If prime[p] is not changed, then # it is a prime if (prime[p] == True): # Update all multiples of p for i in range(p * 2, max_val+1, p): prime[i] = False # Sum all primes in arr[] sum = 0 for i in range(n): if (prime[arr[i]]): sum += arr[i] return sum # Driver code arr =[1, 2, 3, 4, 5, 6, 7] n = len(arr) print(primeSum(arr, n)) # This code is contributed by mohit kumar 29
C#
// C# program to find sum of // primes in given array. using System; using System.Linq; using System.Collections.Generic; class GFG { // Function to find count of prime static int primeSum(int []arr, int n) { // Find maximum value in the array int max_val = arr.Max(); // USE SIEVE TO FIND ALL PRIME NUMBERS LESS // THAN OR EQUAL TO max_val // Create a boolean array "prime[0..n]". A // value in prime[i] will finally be false // if i is Not a prime, else true. List<bool> prime = new List<bool>(max_val + 1); for(int i = 0; i < max_val + 1; i++) prime.Insert(i,true); // Remaining part of SIEVE prime.Insert(0, false); prime.Insert(1, false); for (int p = 2; p * p <= max_val; p++) { // If prime[p] is not changed, then // it is a prime if (prime[p] == true) { // Update all multiples of p for (int i = p * 2; i <= max_val; i += p) prime.Insert(i,false); } } // Sum all primes in arr[] int sum = 0; for (int i = 0; i < n; i++) if (prime[arr[i]]) sum += arr[i]; return sum; } // Driver code public static void Main(String[] args) { int []arr = { 1, 2, 3, 4, 5, 6, 7 }; int n = arr.Length; Console.WriteLine(primeSum(arr, n)); } } // This code contributed by Rajput-Ji
Javascript
<script> // Javascript program to find sum of // primes in given array. // Function to find count of prime function primeSum(arr, n) { // Find maximum value in the array let max_val = arr.sort((a, b) => b - a)[0]; // USE SIEVE TO FIND ALL PRIME NUMBERS LESS // THAN OR EQUAL TO max_val // Create a boolean array "prime[0..n]". A // value in prime[i] will finally be false // if i is Not a prime, else true. let prime = new Array(max_val + 1).fill(true); // Remaining part of SIEVE prime[0] = false; prime[1] = false; for (let p = 2; p * p <= max_val; p++) { // If prime[p] is not changed, then // it is a prime if (prime[p] == true) { // Update all multiples of p for (let i = p * 2; i <= max_val; i += p) prime[i] = false; } } // Sum all primes in arr[] let sum = 0; for (let i = 0; i < n; i++) if (prime[arr[i]]) sum += arr[i]; return sum; } // Driver code let arr = [1, 2, 3, 4, 5, 6, 7]; let n = arr.length; document.write(primeSum(arr, n)); // This code is contributed by _saurabh_jaiswal. </script>
17
Complejidad del tiempo: O(n*loglogn)
Publicación traducida automáticamente
Artículo escrito por VishalBachchas y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA