Largest perfect cube number in an Array - GeeksforGeeks

15 Apr, 2021
Given an array of N integers. The task is to find the largest number which is a perfect cube. Print -1 if there is no number that is perfect cube.Examples:  
Input : arr[] = {16, 8, 25, 2, 3, 10} 
Output : 25
Explanation: 25 is the largest number 
that is a perfect cube. 

Input : arr[] = {36, 64, 10, 16, 29, 25| 
Output : 64
 
A Simple Solution is to sort the elements and sort the N numbers and start checking from back for a perfect cube number using cbrt() function. The first number from the end 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 at 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 maximum element, and store the maximum of all perfect cubes.Below is the implementation of the above approach:  
C++
Java
Python3
C#
PHP
Javascript
// CPP program to find the largest perfect// cube number among n numbers #include <bits/stdc++.h>using namespace std; // Function to check if a number// is perfect cube number or notbool 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 find the largest perfect// cube number in the arrayint largestPerfectcubeNumber(int a[], int n){    // stores the maximum of all    // perfect cube numbers    int maxi = -1;     // Traverse all elements in the array    for (int i = 0; i < n; i++) {         // store the maximum if current        // element is a perfect cube        if (checkPerfectcube(a[i]))            maxi = max(a[i], maxi);    }     return maxi;} // Driver Codeint main(){    int a[] = { 16, 64, 25, 2, 3, 10 };     int n = sizeof(a) / sizeof(a[0]);     cout << largestPerfectcubeNumber(a, n);     return 0;}
// Java program to find the largest perfect// cube number among n numbersclass Solution{ // Function to check if a number// is perfect cube number or notstatic 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 find the largest perfect// cube number in the arraystatic int largestPerfectcubeNumber(int a[], int n){    // stores the maximum of all    // perfect cube numbers    int maxi = -1;     // Traverse all elements in the array    for (int i = 0; i < n; i++) {         // store the maximum if current        // element is a perfect cube        if (checkPerfectcube(a[i]))            maxi = Math.max(a[i], maxi);    }     return maxi;} // Driver Codepublic static void main(String args[]){    int a[] = { 16, 64, 25, 2, 3, 10 };     int n =a.length;     System.out.print(largestPerfectcubeNumber(a, n)); }} //contributed by Arnab Kundu
# Python 3 program to find the largest# perfect cube number among n numbersimport math # Function to check if a number# is perfect cube number or notdef checkPerfectcube(n):         # checks if it is a perfect    # cube number    cube_root = n**(1./3.)    if round(cube_root) ** 3 == n:        return True             else:        return False # Function to find the largest perfect# cube number in the arraydef largestPerfectcubeNumber(a, n):         # stores the maximum of all    # perfect cube numbers    maxi = -1     # Traverse all elements in the array    for i in range(0, n, 1):                 # store the maximum if current        # element is a perfect cube        if (checkPerfectcube(a[i])):            maxi = max(a[i], maxi)     return maxi; # Driver Codeif __name__ == '__main__':    a = [16, 64, 25, 2, 3, 10]     n = len(a)     print(largestPerfectcubeNumber(a, n)) # This code is contributed by# Surendra_Gangwar
//C# program to find the largest perfect// cube number among n numbersusing System; public class Solution{     // Function to check if a number    // is perfect cube number or not    static bool checkPerfectcube(int n)    {        // takes the sqrt of the number        int d = (int)Math.Ceiling(Math.Pow(n, (double)1 / 3));        // checks if it is a perfect        // cube number        if (d * d * d == n)            return true;         return false;    }     // Function to find the largest perfect    // cube number in the array    static int largestPerfectcubeNumber(int []a, int n)    {        // stores the maximum of all        // perfect cube numbers        int maxi = -1;         // Traverse all elements in the array        for (int i = 0; i < n; i++) {             // store the maximum if current            // element is a perfect cube            if (checkPerfectcube(a[i]))                maxi = Math.Max(a[i], maxi);        }         return maxi;    }     // Driver Code    public static void Main()    {        int []a = { 16, 64, 25, 2, 3, 10 };         int n =a.Length;         Console.WriteLine(largestPerfectcubeNumber(a, n));     }} /*This code is contributed by PrinciRaj1992*/
<?php// PHP program to find the largest perfect// cube number among n numbers // Function to check if a number// is perfect cube number or notfunction checkPerfectcube($n){    // takes the sqrt of the number    $d = pow($n, (1 / 3));    $d = round($d);     // checks if it is a perfect    // cube number    if ($d * $d * $d == $n)        return true;     return false;} // Function to find the largest perfect// cube number in the arrayfunction largestPerfectcubeNumber(&$a, $n){    // stores the maximum of all    // perfect cube numbers    $maxi = -1;     // Traverse all elements in the array    for ($i = 0; $i < $n; $i++)    {         // store the maximum if current        // element is a perfect cube        if (checkPerfectcube($a[$i]))            $maxi = max($a[$i], $maxi);    }     return $maxi;} // Driver Code$a = array( 16, 64, 25, 2, 3, 10 );$n = sizeof($a);echo largestPerfectcubeNumber($a, $n); // This code is contributed by ita_c?>
<script> // Javascript program to find the largest perfect// cube number among n numbers // Function to check if a number// is perfect cube number or notfunction 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 find the largest perfect// cube number in the arrayfunction largestPerfectcubeNumber(a, n){    // stores the maximum of all    // perfect cube numbers    let maxi = -1;     // Traverse all elements in the array    for (let i = 0; i < n; i++) {         // store the maximum if current        // element is a perfect cube        if (checkPerfectcube(a[i]))            maxi = Math.max(a[i], maxi);    }     return maxi;} // Driver Codelet a = [ 16, 64, 25, 2, 3, 10 ]; let n = a.length; document.write(largestPerfectcubeNumber(a, n)); </script>
64
 
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