La clasificación por conteo es una técnica de clasificación basada en claves entre un rango específico. Funciona contando la cantidad de objetos que tienen valores clave distintos (tipo de hashing). Luego haga algo de aritmética para calcular la posición de cada objeto en la secuencia de salida.
Características del tipo de conteo:
- La ordenación por conteo hace suposiciones sobre los datos, por ejemplo, asume que los valores van a estar en el rango de 0 a 10 o 10 a 99, etc. Algunas otras suposiciones que hace la ordenación por conteo son que los datos de entrada serán todos números reales.
- Al igual que otros algoritmos, este algoritmo de clasificación no es un algoritmo basado en la comparación, reduce el valor en una array de conteo temporal y los usa para clasificar.
- Utiliza una array temporal que lo convierte en un algoritmo no in situ .
Entendámoslo con la ayuda de un ejemplo.
C++
// C++ Program for counting sort
#include <bits/stdc++.h>
#include <string.h>
using namespace std;
#define RANGE 255
// The main function that sort
// the given string arr[] in
// alphabetical order
void countSort(char arr[])
{
// The output character array
// that will have sorted arr
char output[strlen(arr)];
// Create a count array to store count of individual
// characters and initialize count array as 0
int count[RANGE + 1], i;
memset(count, 0, sizeof(count));
// Store count of each character
for (i = 0; arr[i]; ++i)
++count[arr[i]];
// Change count[i] so that count[i] now contains actual
// position of this character in output array
for (i = 1; i <= RANGE; ++i)
count[i] += count[i - 1];
// Build the output character array
for (i = 0; arr[i]; ++i) {
output[count[arr[i]] - 1] = arr[i];
--count[arr[i]];
}
/*
For Stable algorithm
for (i = sizeof(arr)-1; i>=0; --i)
{
output[count[arr[i]]-1] = arr[i];
--count[arr[i]];
}
For Logic : See implementation
*/
// Copy the output array to arr, so that arr now
// contains sorted characters
for (i = 0; arr[i]; ++i)
arr[i] = output[i];
}
// Driver code
int main()
{
char arr[] = "geeksforgeeks";
countSort(arr);
cout << "Sorted character array is " << arr;
return 0;
}
// This code is contributed by rathbhupendra
C
// C Program for counting sort
#include <stdio.h>
#include <string.h>
#define RANGE 255
// The main function that sort the given string arr[] in
// alphabetical order
void countSort(char arr[])
{
// The output character array that will have sorted arr
char output[strlen(arr)];
// Create a count array to store count of individual
// characters and initialize count array as 0
int count[RANGE + 1], i;
memset(count, 0, sizeof(count));
// Store count of each character
for (i = 0; arr[i]; ++i)
++count[arr[i]];
// Change count[i] so that count[i] now contains actual
// position of this character in output array
for (i = 1; i <= RANGE; ++i)
count[i] += count[i - 1];
// Build the output character array
for (i = 0; arr[i]; ++i) {
output[count[arr[i]] - 1] = arr[i];
--count[arr[i]];
}
/*
For Stable algorithm
for (i = sizeof(arr)-1; i>=0; --i)
{
output[count[arr[i]]-1] = arr[i];
--count[arr[i]];
}
For Logic : See implementation
*/
// Copy the output array to arr, so that arr now
// contains sorted characters
for (i = 0; arr[i]; ++i)
arr[i] = output[i];
}
// Driver program to test above function
int main()
{
char arr[] = "geeksforgeeks"; //"applepp";
countSort(arr);
printf("Sorted character array is %sn", arr);
return 0;
}
Java
// Java implementation of Counting Sort
class CountingSort {
void sort(char arr[])
{
int n = arr.length;
// The output character array that will have sorted arr
char output[] = new char[n];
// Create a count array to store count of individual
// characters and initialize count array as 0
int count[] = new int[256];
for (int i = 0; i < 256; ++i)
count[i] = 0;
// store count of each character
for (int i = 0; i < n; ++i)
++count[arr[i]];
// Change count[i] so that count[i] now contains actual
// position of this character in output array
for (int i = 1; i <= 255; ++i)
count[i] += count[i - 1];
// Build the output character array
// To make it stable we are operating in reverse order.
for (int i = n - 1; i >= 0; i--) {
output[count[arr[i]] - 1] = arr[i];
--count[arr[i]];
}
// Copy the output array to arr, so that arr now
// contains sorted characters
for (int i = 0; i < n; ++i)
arr[i] = output[i];
}
// Driver method
public static void main(String args[])
{
CountingSort ob = new CountingSort();
char arr[] = { 'g', 'e', 'e', 'k', 's', 'f', 'o',
'r', 'g', 'e', 'e', 'k', 's' };
ob.sort(arr);
System.out.print("Sorted character array is ");
for (int i = 0; i < arr.length; ++i)
System.out.print(arr[i]);
}
}
/*This code is contributed by Rajat Mishra */
Python3
# Python program for counting sort
# The main function that sort the given string arr[] in
# alphabetical order
def countSort(arr):
# The output character array that will have sorted arr
output = [0 for i in range(len(arr))]
# Create a count array to store count of individual
# characters and initialize count array as 0
count = [0 for i in range(256)]
# For storing the resulting answer since the
# string is immutable
ans = ["" for _ in arr]
# Store count of each character
for i in arr:
count[ord(i)] += 1
# Change count[i] so that count[i] now contains actual
# position of this character in output array
for i in range(256):
count[i] += count[i-1]
# Build the output character array
for i in range(len(arr)):
output[count[ord(arr[i])]-1] = arr[i]
count[ord(arr[i])] -= 1
# Copy the output array to arr, so that arr now
# contains sorted characters
for i in range(len(arr)):
ans[i] = output[i]
return ans
# Driver program to test above function
arr = "geeksforgeeks"
ans = countSort(arr)
print("Sorted character array is % s" %("".join(ans)))
# This code is contributed by Nikhil Kumar Singh
C#
// C# implementation of Counting Sort
using System;
class GFG {
static void countsort(char[] arr)
{
int n = arr.Length;
// The output character array that
// will have sorted arr
char[] output = new char[n];
// Create a count array to store
// count of individual characters
// and initialize count array as 0
int[] count = new int[256];
for (int i = 0; i < 256; ++i)
count[i] = 0;
// store count of each character
for (int i = 0; i < n; ++i)
++count[arr[i]];
// Change count[i] so that count[i]
// now contains actual position of
// this character in output array
for (int i = 1; i <= 255; ++i)
count[i] += count[i - 1];
// Build the output character array
// To make it stable we are operating in reverse order.
for (int i = n - 1; i >= 0; i--) {
output[count[arr[i]] - 1] = arr[i];
--count[arr[i]];
}
// Copy the output array to arr, so
// that arr now contains sorted
// characters
for (int i = 0; i < n; ++i)
arr[i] = output[i];
}
// Driver method
public static void Main()
{
char[] arr = { 'g', 'e', 'e', 'k', 's', 'f', 'o',
'r', 'g', 'e', 'e', 'k', 's' };
countsort(arr);
Console.Write("Sorted character array is ");
for (int i = 0; i < arr.Length; ++i)
Console.Write(arr[i]);
}
}
// This code is contributed by Sam007.
PHP
<?php
// PHP Program for counting sort
$RANGE = 255;
// The main function that sort
// the given string arr[] in
// alphabetical order
function countSort($arr)
{
global $RANGE;
// The output character array
// that will have sorted arr
$output = array(strlen($arr));
$len = strlen($arr);
// Create a count array to
// store count of individual
// characters and initialize
// count array as 0
$count = array_fill(0, $RANGE + 1, 0);
// Store count of
// each character
for($i = 0; $i < $len; ++$i)
++$count[ord($arr[$i])];
// Change count[i] so that
// count[i] now contains
// actual position of this
// character in output array
for ($i = 1; $i <= $RANGE; ++$i)
$count[$i] += $count[$i - 1];
// Build the output
// character array
// To make it stable we are operating
// in reverse order.
for ($i = $len-1; $i >= 0 ; $i--)
{
$output[$count[ord($arr[$i])] - 1] = $arr[$i];
--$count[ord($arr[$i])];
}
// Copy the output array to
// arr, so that arr now
// contains sorted characters
for ($i = 0; $i < $len; ++$i)
$arr[$i] = $output[$i];
return $arr;
}
// Driver Code
$arr = "geeksforgeeks"; //"applepp";
$arr = countSort($arr);
echo "Sorted character array is " . $arr;
// This code is contributed by mits
?>
Javascript
Javas<script>
// Javascript implementation of Counting Sort
function sort(arr)
{
var n = arr.length;
// The output character array that will have sorted arr
var output = Array.from({length: n}, (_, i) => 0);
// Create a count array to store count of individual
// characters and initialize count array as 0
var count = Array.from({length: 256}, (_, i) => 0);
// store count of each character
for (var i = 0; i < n; ++i)
++count[arr[i].charCodeAt(0)];
// Change count[i] so that count[i] now contains actual
// position of this character in output array
for (var i = 1; i <= 255; ++i)
count[i] += count[i - 1];
// Build the output character array
// To make it stable we are operating in reverse order.
for (var i = n - 1; i >= 0; i--) {
output[count[arr[i].charCodeAt(0)] - 1] = arr[i];
--count[arr[i].charCodeAt(0)];
}
// Copy the output array to arr, so that arr now
// contains sorted characters
for (var i = 0; i < n; ++i)
arr[i] = output[i];
return arr;
}
// Driver method
var arr = [ 'g', 'e', 'e', 'k', 's', 'f', 'o',
'r', 'g', 'e', 'e', 'k', 's' ];
arr = sort(arr);
document.write("Sorted character array is ");
for (var i = 0; i < arr.length; ++i)
document.write(arr[i]);
// This code is contributed by shikhasingrajput
</script>
cript
C++
// Counting sort which takes negative numbers as well
#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;
void countSort(vector<int>& arr)
{
int max = *max_element(arr.begin(), arr.end());
int min = *min_element(arr.begin(), arr.end());
int range = max - min + 1;
vector<int> count(range), output(arr.size());
for (int i = 0; i < arr.size(); i++)
count[arr[i] - min]++;
for (int i = 1; i < count.size(); i++)
count[i] += count[i - 1];
for (int i = arr.size() - 1; i >= 0; i--) {
output[count[arr[i] - min] - 1] = arr[i];
count[arr[i] - min]--;
}
for (int i = 0; i < arr.size(); i++)
arr[i] = output[i];
}
void printArray(vector<int>& arr)
{
for (int i = 0; i < arr.size(); i++)
cout << arr[i] << " ";
cout << "\n";
}
int main()
{
vector<int> arr = { -5, -10, 0, -3, 8, 5, -1, 10 };
countSort(arr);
printArray(arr);
return 0;
}
Java
// Counting sort which takes negative numbers as well
import java.util.*;
class GFG {
static void countSort(int[] arr)
{
int max = Arrays.stream(arr).max().getAsInt();
int min = Arrays.stream(arr).min().getAsInt();
int range = max - min + 1;
int count[] = new int[range];
int output[] = new int[arr.length];
for (int i = 0; i < arr.length; i++) {
count[arr[i] - min]++;
}
for (int i = 1; i < count.length; i++) {
count[i] += count[i - 1];
}
for (int i = arr.length - 1; i >= 0; i--) {
output[count[arr[i] - min] - 1] = arr[i];
count[arr[i] - min]--;
}
for (int i = 0; i < arr.length; i++) {
arr[i] = output[i];
}
}
static void printArray(int[] arr)
{
for (int i = 0; i < arr.length; i++) {
System.out.print(arr[i] + " ");
}
System.out.println("");
}
// Driver code
public static void main(String[] args)
{
int[] arr = { -5, -10, 0, -3, 8, 5, -1, 10 };
countSort(arr);
printArray(arr);
}
}
// This code is contributed by princiRaj1992
Python3
# Python program for counting sort
# which takes negative numbers as well
# The function that sorts the given arr[]
def count_sort(arr):
max_element = int(max(arr))
min_element = int(min(arr))
range_of_elements = max_element - min_element + 1
# Create a count array to store count of individual
# elements and initialize count array as 0
count_arr = [0 for _ in range(range_of_elements)]
output_arr = [0 for _ in range(len(arr))]
# Store count of each character
for i in range(0, len(arr)):
count_arr[arr[i]-min_element] += 1
# Change count_arr[i] so that count_arr[i] now contains actual
# position of this element in output array
for i in range(1, len(count_arr)):
count_arr[i] += count_arr[i-1]
# Build the output character array
for i in range(len(arr)-1, -1, -1):
output_arr[count_arr[arr[i] - min_element] - 1] = arr[i]
count_arr[arr[i] - min_element] -= 1
# Copy the output array to arr, so that arr now
# contains sorted characters
for i in range(0, len(arr)):
arr[i] = output_arr[i]
return arr
# Driver program to test above function
arr = [-5, -10, 0, -3, 8, 5, -1, 10]
ans = count_sort(arr)
print("Sorted character array is " + str(ans))
C#
// Counting sort which takes negative numbers as well
using System;
using System.Collections.Generic;
using System.Linq;
class GFG
{
static void countSort(int[] arr)
{
int max = arr.Max();
int min = arr.Min();
int range = max - min + 1;
int []count = new int[range];
int []output = new int[arr.Length];
for (int i = 0; i < arr.Length; i++) {
count[arr[i] - min]++;
}
for (int i = 1; i < count.Length; i++) {
count[i] += count[i - 1];
}
for (int i = arr.Length - 1; i >= 0; i--) {
output[count[arr[i] - min] - 1] = arr[i];
count[arr[i] - min]--;
}
for (int i = 0; i < arr.Length; i++) {
arr[i] = output[i];
}
}
static void printArray(int[] arr)
{
for (int i = 0; i < arr.Length; i++)
{
Console.Write(arr[i] + " ");
}
Console.WriteLine("");
}
// Driver code
public static void Main(string[] args)
{
int[] arr = { -5, -10, 0, -3, 8, 5, -1, 10 };
countSort(arr);
printArray(arr);
}
}
// This code is contributed by rutvik_56.
Javascript
<script>
// Counting sort which takes negative numbers as well
function countSort(arr)
{
var max = Math.max.apply(Math, arr);
var min = Math.min.apply(Math, arr);
var range = max - min + 1;
var count = Array.from({length: range}, (_, i) => 0);
var output = Array.from({length: arr.length}, (_, i) => 0);
for (i = 0; i < arr.length; i++) {
count[arr[i] - min]++;
}
for (i = 1; i < count.length; i++) {
count[i] += count[i - 1];
}
for (i = arr.length - 1; i >= 0; i--) {
output[count[arr[i] - min] - 1] = arr[i];
count[arr[i] - min]--;
}
for (i = 0; i < arr.length; i++) {
arr[i] = output[i];
}
}
function printArray(arr)
{
for (i = 0; i < arr.length; i++)
{
document.write(arr[i] + " ");
}
document.write('<br>');
}
// Driver code
var arr = [ -5, -10, 0, -3, 8, 5, -1, 10 ];
countSort(arr);
printArray(arr);
// This code is contributed by Amit Katiyar
</script>
Publicación traducida automáticamente
Artículo escrito por GeeksforGeeks-1 y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA