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6. Counting sort.cpp
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6. Counting sort.cpp
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#include<iostream>
using namespace std;
int getMax(int a[], int n)
{
int max = a[0];
for(int i = 1; i<n; i++)
{
if(a[i] > max)
max = a[i];
}
return max; //maximum element from the array
}
void countSort(int a[], int n) // function to perform counting sort
{
int output[n+1];
int max = getMax(a, n);
int count[max+1]; //create count array with size [max+1]
for (int i = 0; i <= max; ++i)
{
count[i] = 0; // Initialize count array with all zeros
}
for (int i = 0; i < n; i++) // Store the count of each element
{
count[a[i]]++;
}
for(int i = 1; i<=max; i++)
count[i] += count[i-1]; //find cumulative frequency
for (int i = n - 1; i >= 0; i--)
{
output[--count[a[i]]] = a[i];
}
for(int i = 0; i<n; i++) {
a[i] = output[i]; //store the sorted elements into main array
}
}
void printArr(int a[], int n) /* function to print the array */
{
int i;
for (i = 0; i < n; i++)
cout<<a[i]<<" ";
}
int main() {
int a[] = { 11, 30, 24, 7, 31, 16 };
int n = sizeof(a)/sizeof(a[0]);
cout<<"Before sorting array elements are"<<endl;
printArr(a, n);
countSort(a, n);
cout<<"After sorting array elements are"<<endl;
printArr(a, n);
return 0;
}