Untitled

#include <stdlib.h>#include <stdio.h>#include <string.h>#include <ctype.h>#include <math.h>#include <limits.h>#include <assert.h>#include <algorithm>char a[1 << 18 + 1];char f[1 << 18];void compute_f_helper(int l, int i, char *result) {    char *tmp = (char *) malloc((l / 2) * sizeof(*tmp));        if (l == 1) {        *result = (a[i] == '1');        return;    }        compute_f_helper(l / 2, i, result);        memcpy(result + l / 2, result, (l / 2) * sizeof(*tmp));        compute_f_helper(l / 2, i + l / 2, tmp);        for (int j = 0; j < l / 2; j++) {        result[l / 2 + j] ^= tmp[j];    }        free(tmp);}void compute_f(int l) {    char *tmp = (char *)malloc((l / 2) * sizeof(*tmp));        compute_f_helper(l / 2, 0, f);    memcpy(f + l / 2, f, (l / 2) * sizeof(*tmp));        compute_f_helper(l / 2, l / 2, tmp);        for (int i = 0; i < l / 2; i++) {        f[l / 2 + i] ^= tmp[i];    }        free(tmp);}int count_result(int n, int k, int mask = 0) {    if (n < k - 1)        return 0;    if (k == 0) {        return f[mask];    }        return count_result(n - 1, k, mask) + count_result(n - 1, k - 1, mask | (1 << n));}int main (int argc, char **argv){    int N;    scanf("%d", &N);        int n;    int k;    for (int i = 0; i < N; i++) {        scanf("%d", &n);        scanf("%d", &k);        if (n == 0) {            printf("0\n");            continue;        }        for (int j = 0; j < (1 << n); j++) {            scanf(" %c", &(a[j]));        }        //scanf("%s", a);                compute_f(1 << n);                printf("%d\n", count_result(n, k));    }        return 0;}