Count of greater elements for each element in the Array
Last Updated :
13 Sep, 2022
Given an array arr of integers of size N, the task is to find, for every element, the number of elements that are greater than it.
Examples:
Input: arr[] = {4, 6, 2, 1, 8, 7}
Output: {3, 2, 4, 5, 0, 1}
Input: arr[] = {2, 3, 4, 5, 6, 7, 8}
Output: {6, 5, 4, 3, 2, 1, 0}
Approach: Store the frequencies of every array element using a Map. Iterate the Map in reverse and store the sum of the frequency of all previously traversed elements (i.e. elements greater than it) for every element.
Below code is the implementation of the above approach:
C++
#include <bits/stdc++.h>
using namespace std;
void countOfGreaterElements( int arr[], int n)
{
map< int , int > mp;
for ( int i = 0; i < n; i++) {
mp[arr[i]]++;
}
int x = 0;
for ( auto it = mp.rbegin(); it != mp.rend(); it++) {
int temp = it->second;
mp[it->first] = x;
x += temp;
}
for ( int i = 0; i < n; i++)
cout << mp[arr[i]] << " " ;
}
int main()
{
int arr[] = { 7, 9, 5, 2, 1, 3, 4, 8, 6 };
int n = sizeof (arr) / sizeof (arr[0]);
countOfGreaterElements(arr, n);
return 0;
}
|
Java
import java.util.*;
class GfG {
public static void countOfGreaterElements( int arr[])
{
int n = arr.length;
TreeMap<Integer, Integer> mp = new TreeMap<Integer, Integer>(Collections.reverseOrder());
for ( int i = 0 ; i < n; i++) {
mp.put(arr[i], mp.getOrDefault(arr[i], 0 ) + 1 );
}
int x = 0 ;
for (Map.Entry<Integer, Integer> e : mp.entrySet()) {
Integer temp = e.getValue();
mp.put(e.getKey(), x);
x += temp;
}
for ( int i = 0 ; i < n; i++)
System.out.print(mp.get(arr[i]) + " " );
}
public static void main(String args[])
{
int arr[] = { 7 , 9 , 5 , 2 , 1 , 3 , 4 , 8 , 6 };
countOfGreaterElements(arr);
}
}
|
Python 3
def countOfGreaterElements(arr, n):
mp = {i: 0 for i in range ( 1000 )}
for i in range (n):
mp[arr[i]] + = 1
x = 0
p = []
q = []
m = []
for key, value in mp.items():
m.append([key, value])
m = m[:: - 1 ]
for p in m:
temp = p[ 1 ]
mp[p[ 0 ]] = x
x + = temp
for i in range (n):
print (mp[arr[i]], end = " " )
if __name__ = = '__main__' :
arr = [ 7 , 9 , 5 , 2 , 1 , 3 , 4 , 8 , 6 ]
n = len (arr)
countOfGreaterElements(arr, n)
|
C#
using System;
using System.Collections.Generic;
class GfG {
public static void countOfGreaterElements( int [] arr)
{
int n = arr.Length;
SortedDictionary< int , int > mp =
new SortedDictionary< int , int >();
for ( int i = 0; i < n; i++) {
int temp = 0;
if (mp.ContainsKey(arr[i]))
{
temp = mp[arr[i]];
mp.Remove(arr[i]);
}
mp[arr[i]] = temp + 1;
}
int x = 0;
var k1 = mp.Keys;
int [] keys = new int [mp.Count];
k1.CopyTo(keys, 0);
Array.Reverse(keys);
foreach ( var e in keys) {
int temp = mp[e];
mp.Remove(e);
mp[e] = x;
x += temp;
}
for ( int i = 0; i < n; i++)
Console.Write(mp[arr[i]] + " " );
}
public static void Main( string [] args)
{
int [] arr = { 7, 9, 5, 2, 1, 3, 4, 8, 6 };
countOfGreaterElements(arr);
}
}
|
Javascript
function countOfGreaterElements(arr, n)
{
let mp = {}
for ( var i = 0; i < n; i++)
{
if (!mp.hasOwnProperty(arr[i]))
mp[arr[i]] = 0
mp[arr[i]] = mp[arr[i]] + 1
}
let x = 0
let m = []
for ( var [key, value] of Object.entries(mp))
{
key = parseInt(key)
value = parseInt(value)
m.push([key, value])
}
for ( var i = m.length - 1; i >= 0; i--)
{
var p = m[i]
var temp = p[1]
mp[p[0]] = x
x += temp
}
for ( var i = 0; i < n; i++)
process.stdout.write(mp[arr[i]] + " " )
}
let arr = [7, 9, 5, 2, 1, 3, 4, 8, 6]
let n = arr.length
countOfGreaterElements(arr, n)
|
Output:
2 0 4 7 8 6 5 1 3
Time Complexity: O(N log(N))
Auxiliary Space: O(N)
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