ssanina

#include <iostream>
#include <stdio.h>
#include <stdlib.h>

int reduce(int (*f)(int, int), int* a, int n)
{
    int res = 0;
    for (int i = 0; i < n; i++)
        res = f(res, a[i]);
    return res;
}

int* map(int (*f)(int), int* a, int n)
{
    int* res;
    res = (int*)calloc(n, sizeof(int));
    for (int i = 0; i < n; i++)
        res[i] = f(a[i]);
    return res;
}

int* filter(int (*f)(int), int* a, int n, int* k)
{
    int* res = NULL;
    *k = 0;
    for (int i = 0; i < n; i++)
    {
        if (f(a[i]))
        {
            res = (int*)realloc(res, (*k + 1) * sizeof(int));
            res[(*k)] = a[i];
            (*k)++;
        }
    }
    return res;
}

int f_sum(int a, int b)
{
    return a + b;
}

int inc(int a)
{
    return ++a;
}

int even(int a)
{
    return (a % 2 == 0);
}

int main()
{
    int* a;
    int n;
    scanf_s("%d", &n);
    a = (int*)calloc(n, sizeof(int));
    for (int i = 0; i < n; i++)
        scanf_s("%d", &a[i]);
    int res1, * res2, * res3;
    res1 = reduce(f_sum, a, n);
    printf("Reduce:\n%d\n", res1);
    res2 = map(inc, a, n);
    printf("Map:\n");
    for (int i = 0; i < n; i++)
        printf("%d ", res2[i]);
    puts("");
    printf("Filter:\n");
    int k;
    res3 = filter(even, a, n, &k);
    for (int i = 0; i < k; i++)
        printf("%d ", res3[i]);
    free(a);
    free(res2);
    free(res3);
    return 0;
}