Callback Sort
Medium
C
Functions
33 views
Problem Statement
Create a generic function to sort the array that accepts a comparison function as a callback. Implement both ascending and descending using different callbacks.
Input Format
An array of elements, array size, and a comparison function (callback).
Output Format
The sorted array based on the comparison logic (ascending or descending).
Example
Array: [5, 2, 9, 1] Comparison: ascending
[1, 2, 5, 9]
Constraints
• Array size ≥ 1
• Comparison function must define ordering
• Comparison function must define ordering
Concept Explanation
The sorting function does not decide order itself.
It uses a callback comparison function to decide how two elements should be ordered.
It uses a callback comparison function to decide how two elements should be ordered.
Step-by-Step Explanation
1.Create a generic sort function that receives:
• Array
• Size of array
• Comparison function
2.Inside the sort function, compare two elements using the callback.
3.If the comparison function indicates wrong order:
• Swap the elements.
4.Repeat comparisons until the array is fully sorted.
5.For ascending order:
• Callback returns true when first element is greater than second.
6.For descending order:
• Callback returns true when first element is smaller than second.
7.Pass the required callback to the sort function to get desired order.
• Array
• Size of array
• Comparison function
2.Inside the sort function, compare two elements using the callback.
3.If the comparison function indicates wrong order:
• Swap the elements.
4.Repeat comparisons until the array is fully sorted.
5.For ascending order:
• Callback returns true when first element is greater than second.
6.For descending order:
• Callback returns true when first element is smaller than second.
7.Pass the required callback to the sort function to get desired order.
Concept Explanation
The sorting function does not decide order itself.
It uses a callback comparison function to decide how two elements should be ordered.
It uses a callback comparison function to decide how two elements should be ordered.
Step-by-Step Explanation
1.Create a generic sort function that receives:
• Array
• Size of array
• Comparison function
2.Inside the sort function, compare two elements using the callback.
3.If the comparison function indicates wrong order:
• Swap the elements.
4.Repeat comparisons until the array is fully sorted.
5.For ascending order:
• Callback returns true when first element is greater than second.
6.For descending order:
• Callback returns true when first element is smaller than second.
7.Pass the required callback to the sort function to get desired order.
• Array
• Size of array
• Comparison function
2.Inside the sort function, compare two elements using the callback.
3.If the comparison function indicates wrong order:
• Swap the elements.
4.Repeat comparisons until the array is fully sorted.
5.For ascending order:
• Callback returns true when first element is greater than second.
6.For descending order:
• Callback returns true when first element is smaller than second.
7.Pass the required callback to the sort function to get desired order.
Input / Output Format
Input Format
An array of elements, array size, and a comparison function (callback).
Output Format
The sorted array based on the comparison logic (ascending or descending).
Constraints
• Array size ≥ 1
• Comparison function must define ordering
• Comparison function must define ordering
Examples
Input:
Array: [5, 2, 9, 1]
Comparison: ascending
Output:
[1, 2, 5, 9]
Example Solution (Public)
#include <stdio.h>
/* Comparison function type */
typedef int (*CompareFunc)(int, int);
/* Ascending comparison */
int ascending(int a, int b) {
return a - b; // positive if a > b, negative if a < b
}
/* Descending comparison */
int descending(int a, int b) {
return b - a; // positive if b > a, negative if b < a
}
/* Generic bubble sort function */
void sort(int arr[], int n, CompareFunc cmp) {
int i, j, temp;
for (i = 0; i < n - 1; i++) {
for (j = 0; j < n - i - 1; j++) {
if (cmp(arr[j], arr[j + 1]) > 0) {
temp = arr[j];
arr[j] = arr[j + 1];
arr[j + 1] = temp;
}
}
}
}
/* Function to print an array */
void printArray(int arr[], int n) {
for (int i = 0; i < n; i++)
printf("%d ", arr[i]);
printf("n");
}
int main() {
int arr1[] = {5, 2, 9, 1, 7};
int arr2[] = {5, 2, 9, 1, 7};
int n = 5;
printf("Original array: ");
printArray(arr1, n);
/* Sort ascending */
sort(arr1, n, ascending);
printf("Ascending sort: ");
printArray(arr1, n);
/* Sort descending */
sort(arr2, n, descending);
printf("Descending sort: ");
printArray(arr2, n);
return 0;
}
Official Solution Code
#include <stdio.h>
/* Comparison function type */
typedef int (*CompareFunc)(int, int);
/* Ascending comparison */
int ascending(int a, int b) {
return a - b; // positive if a > b, negative if a < b
}
/* Descending comparison */
int descending(int a, int b) {
return b - a; // positive if b > a, negative if b < a
}
/* Generic bubble sort function */
void sort(int arr[], int n, CompareFunc cmp) {
int i, j, temp;
for (i = 0; i < n - 1; i++) {
for (j = 0; j < n - i - 1; j++) {
if (cmp(arr[j], arr[j + 1]) > 0) {
temp = arr[j];
arr[j] = arr[j + 1];
arr[j + 1] = temp;
}
}
}
}
/* Function to print an array */
void printArray(int arr[], int n) {
for (int i = 0; i < n; i++)
printf("%d ", arr[i]);
printf("n");
}
int main() {
int arr1[] = {5, 2, 9, 1, 7};
int arr2[] = {5, 2, 9, 1, 7};
int n = 5;
printf("Original array: ");
printArray(arr1, n);
/* Sort ascending */
sort(arr1, n, ascending);
printf("Ascending sort: ");
printArray(arr1, n);
/* Sort descending */
sort(arr2, n, descending);
printf("Descending sort: ");
printArray(arr2, n);
return 0;
}
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