Given an array arr[] of n integers. The task is to find the smallest perfect cube from the array. Print -1 if there is no perfect cube in the array.
Examples:
Input: arr[] = {16, 8, 25, 2, 3, 10}
Output: 8
8 is the only perfect cube in the arrayInput: arr[] = {27, 8, 1, 64}
Output: 1
All elements are perfect cubes but 1 is the minimum of all.
A simple solution is to sort the elements and sort the numbers and start checking from start for a perfect cube number using cbrt() function. The first number from the beginning which is a perfect cube number is our answer. The complexity of sorting is O(n log n) and of cbrt() function is log n, so in the worst case, the complexity is O(n log n).
An efficient solution is to iterate for all the elements in O(n) and compare every time with the minimum element and store the minimum of all perfect cubes.
Below is the implementation of the above approach:
C++
// C++ implementation of the approach#include <bits/stdc++.h>using namespace std;// Function that returns true// if n is a perfect cubebool checkPerfectcube(int n){ // Takes the sqrt of the number int d = cbrt(n); // Checks if it is a perfect // cube number if (d * d * d == n) return true; return false;}// Function to return the smallest perfect// cube from the arrayint smallestPerfectCube(int a[], int n){ // Stores the minimum of all the // perfect cubes from the array int mini = INT_MAX; // Traverse all elements in the array for (int i = 0; i < n; i++) { // Store the minimum if current // element is a perfect cube if (checkPerfectcube(a[i])) { mini = min(a[i], mini); } } return mini;}// Driver codeint main(){ int a[] = { 16, 8, 25, 2, 3, 10 }; int n = sizeof(a) / sizeof(a[0]); cout << smallestPerfectCube(a, n); return 0;} |
Java
// Java implementation of the approachimport java.io.*;class GFG { // Function that returns true // if n is a perfect cube static boolean checkPerfectcube(int n) { // Takes the sqrt of the number int d = (int)Math.cbrt(n); // Checks if it is a perfect // cube number if (d * d * d == n) return true; return false; } // Function to return the smallest perfect // cube from the array static int smallestPerfectCube(int a[], int n) { // Stores the minimum of all the // perfect cubes from the array int mini = Integer.MAX_VALUE; // Traverse all elements in the array for (int i = 0; i < n; i++) { // Store the minimum if current // element is a perfect cube if (checkPerfectcube(a[i])) { mini = Math.min(a[i], mini); } } return mini; } // Driver code public static void main(String[] args) { int a[] = { 16, 8, 25, 2, 3, 10 }; int n = a.length; System.out.print(smallestPerfectCube(a, n)); }}// This code is contributed by anuj_67.. |
Python3
# Python3 implementation of the approachimport sys# Function that returns true# if n is a perfect cubedef checkPerfectcube(n): # Takes the sqrt of the number d = int(n**(1/3)) # Checks if it is a perfect # cube number if (d * d * d == n): return True return False# Function to return the smallest perfect# cube from the arraydef smallestPerfectCube(a, n): # Stores the minimum of all the # perfect cubes from the array mini = sys.maxsize # Traverse all elements in the array for i in range(n): # Store the minimum if current # element is a perfect cube if (checkPerfectcube(a[i])): mini = min(a[i], mini) return mini# Driver codeif __name__ == "__main__": a = [16, 8, 25, 2, 3, 10] n = len(a) print(smallestPerfectCube(a, n))# This code is contributed by AnkitRai01 |
C#
// C# implementation of the approachusing System;class GFG { // Function that returns true // if n is a perfect cube static bool checkPerfectcube(int n) { // Takes the sqrt of the number int d = (int)Math.Sqrt(n); // Checks if it is a perfect // cube number if (d * d * d == n) return true; return false; } // Function to return the smallest perfect // cube from the array static int smallestPerfectCube(int[] a, int n) { // Stores the minimum of all the // perfect cubes from the array int mini = int.MaxValue; // Traverse all elements in the array for (int i = 0; i < n; i++) { // Store the minimum if current // element is a perfect cube if (checkPerfectcube(a[i])) { mini = Math.Min(a[i], mini); } } return mini; } // Driver code static public void Main() { int[] a = { 16, 8, 25, 2, 3, 10 }; int n = a.Length; Console.Write(smallestPerfectCube(a, n)); }}// This code is contributed by ajit.. |
Javascript
<script>// Javascript implementation of the approach// Function that returns true// if n is a perfect cubefunction checkPerfectcube(n){ // Takes the sqrt of the number let d = parseInt(Math.cbrt(n)); // Checks if it is a perfect // cube number if (d * d * d == n) return true; return false;}// Function to return the smallest perfect// cube from the arrayfunction smallestPerfectCube(a, n){ // Stores the minimum of all the // perfect cubes from the array let mini = Number.MAX_VALUE; // Traverse all elements in the array for (let i = 0; i < n; i++) { // Store the minimum if current // element is a perfect cube if (checkPerfectcube(a[i])) { mini = Math.min(a[i], mini); } } return mini;}// Driver codelet a = [ 16, 8, 25, 2, 3, 10 ];let n = a.length;document.write(smallestPerfectCube(a, n));</script> |
Output:
8
Time Complexity: O(n log n) because the inbuilt cbrt function is used
Auxiliary Space: O(1)
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