Untitled

#include <stdio.h>

int f1(int a[], int n);
void f2(int a[], int n);
void f3(int a[], int n);
int f4(int a[], int n);

int main()
{
    int f1();
    void f2();
    void f3();
    int f4();

}

int f1(int a[], int n) 
   {
    // Base case: if array size is less than 3, no numbers can be compared
    if (n < 3) {
        return 0;
    }

    int count = 0;
    // Recursive case: compare numbers to their neighbors
    for (int i = 1; i < n - 1; i++) {
        if ((a[i] > a[i-1] && a[i] > a[i+1]) || (a[i] < a[i-1] && a[i] < a[i+1])) {
            count++;
        }
    }

    // Recursively call f1 with a smaller array
    return count + f1(a+1, n-2);
}

void f2(int a[], int n)
{
    int count[4] = { 0 }; // An array to keep track of how many times each number appears in the array

    // Counting the occurrences of each number in the array
    for (int i = 0; i < n; i++) {
        count[a[i]]++;
    }

    // Filling the array in the appropriate order
    int index = 0;
    for (int j = 0; j <= 3; j++) {
        for (int k = 0; k < count[j]; k++) 
        {
            a[index++] = j;
        }
    }
}

void f3(int a[], int n) // This function takes an array and its length as input parameters
{
    int i, j, temp; // Declare three integer variables i, j, and temp

    // First pass: move all 0s to the front of the array
    j = 0; // Set j to 0 to keep track of the index of the first non-zero element
    for (i = 0; i < n; i++) { // Iterate over the array
        if (a[i] == 0) { // If the element is 0
            temp = a[i]; // Swap the element with the first non-zero element
            a[i] = a[j];
            a[j] = temp;
            j++; // Move the index of the first non-zero element
        }
    }

    // Second pass: move all 1s after the 0s
    for (i = j; i < n; i++) { // Iterate over the remaining elements in the array
        if (a[i] == 1) { // If the element is 1
            temp = a[i]; // Swap the element with the first non-one element
            a[i] = a[j];
            a[j] = temp;
            j++; // Move the index of the first non-one element
        }
    }

    // Third pass: move all 2s after the 1s
    for (i = j; i < n; i++) { // Iterate over the remaining elements in the array
        if (a[i] == 2) { // If the element is 2
            temp = a[i]; // Swap the element with the first non-two element
            a[i] = a[j];
            a[j] = temp;
            j++; // Move the index of the first non-two element
        }
    }
}

int f4(int a[], int n) {
    int i, j, temp;
    // Sort the array a in ascending order using bubble sort algorithm
    for (i = 0; i < n - 1; i++) {
        for (j = 0; j < n - i - 1; j++) {
            if (a[j] > a[j + 1]) {
                temp = a[j];
                a[j] = a[j + 1];
                a[j + 1] = temp;
            }
        }
    }
    // Check if the sorted array contains a continuous sequence of numbers
    for (i = 1; i < n; i++) {
        if (a[i] != a[i - 1] + 1) {
            return 0; // if not, return 0
        }
    }
    return 1; // if yes, return 1
}