#include "stdio.h"
#include "stdlib.h"

void shuffle_swap(int *arr, int n) {
    for (int i = 0; i < 10 * n; ++i) {
        int pos1 = rand() % n;
        int pos2 = rand() % n;
        int t = arr[pos1];
        arr[pos1] = arr[pos2];
        arr[pos2] = t;
    }
}

void shuffle_rev(int *arr, int n) {
    for (int i = 0; i < 10 * n; ++i) {
        int pos1 = rand() % n;
        int pos2 = rand() % n;
        if (pos1 > pos2) {
            int t = pos1;
            pos1 = pos2;
            pos2 = t;
        }
        for (int j = pos1; j <= pos1 + (pos2 - pos1) / 2; ++j) {
            int t = arr[j];
            arr[j] = arr[pos2 - (j - pos1)];
            arr[pos2 - (j - pos1)] = t;
        }
    }
}

int main() {
    srand(time(0));
    int a[20];
    int b[20];
    for (int i = 0; i < 20; ++i) {
        a[i] = i;
        b[i] = i;
    }
    shuffle_swap(a, 20);
    shuffle_rev(b, 20);
    for (int i = 0; i < 20; ++i) {
        printf("%d ", a[i]);
    }
    printf("\n");
    for (int i = 0; i < 20; ++i) {
        printf("%d ", b[i]);
    }
    printf("\n");
}




#include "stdio.h"
#include "stdlib.h"
#include "time.h"

const int MY_RANDMAX = (1 << 15) - 1;

int superRand() {
    return (rand() << 15) + (rand() + rand()) % (1 << 15);
}

int main() {
    srand(time(0));
    int cnt[MY_RANDMAX + 1];
    memset(cnt, 0, sizeof(cnt));
    for (int i = 0; i < MY_RANDMAX + 1; ++i) {
        cnt[superRand() % (MY_RANDMAX + 1)]++;
    }
    int cnt_[10];
    memset(cnt_, 0, sizeof(cnt_));
    int strange = 0;
    for (int i = 0; i < MY_RANDMAX + 1; ++i) {
        if (cnt[i] < 10) {
            cnt_[cnt[i]]++;
            if (cnt[i] >= 7) {
                printf("Number %d occured %d times\n", i, cnt[i]);
            }
        } else {
            strange++;
        }
    }
    for (int i = 0; i < 10; ++i) {
        printf("There are %d numbers that occured %d times\n", cnt_[i], i);
    }
    printf("There are %d strange numbers\n", strange);
    //printf("%d %d\n", RAND_MAX, (1 << 15) - 1);
}