Print numbers in descending order along with their frequencies
Given an array arr, the task is to print the elements of the array in descending order along with their frequencies.
Examples:
Input: arr[] = {1, 3, 3, 3, 4, 4, 5}
Output: 5 occurs 1 times
4 occurs 2 times
3 occurs 3 times
1 occurs 1 times
Input: arr[] = {1, 1, 1, 2, 3, 4, 9, 9, 10}
Output: 10 occurs 1 times
9 occurs 2 times
4 occurs 1 times
3 occurs 1 times
2 occurs 1 times
1 occurs 3 times
Naive approach: Use some Data-Structure (e.g. multiset) which stores elements in decreasing order and then print the elements one by one with it’s count and then erase it from the Data-structure. The time complexity will be O(N log N) and the auxiliary space will be O(N) for the Data-structure used.
Below is the implementation of the above approach:
CPP
// C++ program to print the elements in// descending along with their frequencies#include <bits/stdc++.h>using namespace std;// Function to print the elements in descending// along with their frequenciesvoid printElements(int a[], int n){ // A multiset to store elements in decreasing order multiset<int, greater<int> > ms; // Insert elements in the multiset for (int i = 0; i < n; i++) { ms.insert(a[i]); } // Print the elements along with their frequencies while (!ms.empty()) { // Find the maximum element int maxel = *ms.begin(); // Number of times it occurs int times = ms.count(maxel); cout << maxel << " occurs " << times << " times\n"; // Erase the maxel ms.erase(maxel); }}// Driver Codeint main(){ int a[] = { 1, 1, 1, 2, 3, 4, 9, 9, 10 }; int n = sizeof(a) / sizeof(a[0]); printElements(a, n); return 0;} |
Output:
10 occurs 1 times 9 occurs 2 times 4 occurs 1 times 3 occurs 1 times 2 occurs 1 times 1 occurs 3 times
Efficient Approach: Sort the array in descending order and then start printing the elements from the beginning along with their frequencies.
Below is the implementation of the above approach:
C++
// C++ program to print the elements in// descending along with their frequencies#include <bits/stdc++.h>using namespace std;// Function to print the elements in descending// along with their frequenciesvoid printElements(int a[], int n){ // Sorts the element in decreasing order sort(a, a + n, greater<int>()); int cnt = 1; // traverse the array elements for (int i = 0; i < n - 1; i++) { // Prints the number and count if (a[i] != a[i + 1]) { cout << a[i] << " occurs " << cnt << " times\n"; cnt = 1; } else cnt += 1; } // Prints the last step cout << a[n - 1] << " occurs " << cnt << " times\n";}// Driver Codeint main(){ int a[] = { 1, 1, 1, 2, 3, 4, 9, 9, 10 }; int n = sizeof(a) / sizeof(a[0]); printElements(a, n); return 0;} |
Java
// Java program to print the elements in// descending along with their frequenciesimport java.util.*;class GFG{// Function to print the elements in descending// along with their frequenciesstatic void printElements(int a[], int n){ // Sorts the element in decreasing order Arrays.sort(a); a = reverse(a); int cnt = 1; // traverse the array elements for (int i = 0; i < n - 1; i++) { // Prints the number and count if (a[i] != a[i + 1]) { System.out.print(a[i]+ " occurs " + cnt + " times\n"); cnt = 1; } else cnt += 1; } // Prints the last step System.out.print(a[n - 1]+ " occurs " + cnt + " times\n");}static int[] reverse(int a[]){ int i, n = a.length, t; for (i = 0; i < n / 2; i++) { t = a[i]; a[i] = a[n - i - 1]; a[n - i - 1] = t; } return a;}// Driver Codepublic static void main(String[] args){ int a[] = { 1, 1, 1, 2, 3, 4, 9, 9, 10 }; int n = a.length; printElements(a, n);}}// This code is contributed by PrinciRaj1992 |
Python3
# Python3 program to print the elements in# descending along with their frequencies# Function to print the elements in# descending along with their frequenciesdef printElements(a, n) : # Sorts the element in decreasing order a.sort(reverse = True) cnt = 1 # traverse the array elements for i in range(n - 1) : # Prints the number and count if (a[i] != a[i + 1]) : print(a[i], " occurs ", cnt, "times") cnt = 1 else : cnt += 1 # Prints the last step print(a[n - 1], "occurs", cnt, "times")# Driver Codeif __name__ == "__main__" : a = [ 1, 1, 1, 2, 3, 4, 9, 9, 10 ] n = len(a) printElements(a, n) # This code is contributed by Ryuga |
C#
// C# program to print the elements in// descending along with their frequenciesusing System;class GFG{// Function to print the elements in descending// along with their frequenciesstatic void printElements(int []a, int n){ // Sorts the element in decreasing order Array.Sort(a); a = reverse(a); int cnt = 1; // traverse the array elements for (int i = 0; i < n - 1; i++) { // Prints the number and count if (a[i] != a[i + 1]) { Console.Write(a[i]+ " occurs " + cnt + " times\n"); cnt = 1; } else cnt += 1; } // Prints the last step Console.Write(a[n - 1]+ " occurs " + cnt + " times\n");}static int[] reverse(int []a){ int i, n = a.Length, t; for (i = 0; i < n / 2; i++) { t = a[i]; a[i] = a[n - i - 1]; a[n - i - 1] = t; } return a;}// Driver Codepublic static void Main(String[] args){ int []a = { 1, 1, 1, 2, 3, 4, 9, 9, 10 }; int n = a.Length; printElements(a, n);}}// This code is contributed by PrinciRaj1992 |
PHP
<?php// PHP program to print the elements in// descending along with their frequencies// Function to print the elements in// descending along with their frequenciesfunction printElements(&$a, $n){ // Sorts the element in // decreasing order rsort($a); $cnt = 1; // traverse the array elements for ($i = 0; $i < $n - 1; $i++) { // Prints the number and count if ($a[$i] != $a[$i + 1]) { echo ($a[$i]); echo (" occurs " ); echo $cnt ; echo (" times\n"); $cnt = 1; } else $cnt += 1; } // Prints the last step echo ($a[$n - 1]); echo (" occurs "); echo $cnt; echo (" times\n");}// Driver Code$a = array(1, 1, 1, 2, 3, 4, 9, 9, 10 );$n = sizeof($a);printElements($a, $n);// This code is contributed// by Shivi_Aggarwal?> |
Javascript
<script>// javascript program to print the elements in// descending along with their frequencies // Function to print the elements in descending// along with their frequencies function printElements(a, n) { // Sorts the element in decreasing order a=a.sort(compare); a = reverse(a); var cnt = 1; // traverse the array elements for (var i = 0; i < n - 1; i++) { // Prints the number and count if (a[i] != a[i + 1]) { document.write(a[i]+ " occurs " + cnt + " times" + "<br>"); cnt = 1; } else cnt += 1; } // Prints the last step document.write(a[n - 1]+ " occurs " + cnt + " times" + "<br>");} function reverse(a){ var i, n = a.length, t; for (i = 0; i < n / 2; i++) { t = a[i]; a[i] = a[n - i - 1]; a[n - i - 1] = t; } return a;}function compare(a, b) { if (a < b) { return -1; } else if (a > b) { return 1; } else { return 0; }} // Driver Code var a = [ 1, 1, 1, 2, 3, 4, 9, 9, 10 ]; var n = a.length; printElements(a, n); // This code is contributed by bunnyram19.</script> |
Output:
10 occurs 1 times 9 occurs 2 times 4 occurs 1 times 3 occurs 1 times 2 occurs 1 times 1 occurs 3 times
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