Pukkitappelu battle royale

#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>

struct cell{
    uint64_t pos;
    struct cell *next;
};

int main() {
    uint64_t n = 0;
    uint64_t x = 0;
    if (scanf("%ld %ld", &n, &x) == 0)
        return EXIT_FAILURE;

    if (n == 1){
        return 1;
    }

    struct cell *positions = (struct cell *) calloc(n, sizeof(struct cell));

    for (uint64_t i = 0; i < n; i++){
        positions[i].next = positions + i + 1;
        if (scanf("%ld", &positions[i].pos) == 0)
            return EXIT_FAILURE;
    }
    positions[n-1].next = NULL;

    // main algo

    uint64_t count = 0;
    struct cell *first = positions;
    while (count != 1){
        // printf("\nfirst\n");
        count = 0;
        struct cell *prev = NULL;
        struct cell *cur = first;
        while (cur != NULL){
            if (prev == NULL && cur->next == NULL){
                // printf("1\n");
                count++;
            } else if (prev == NULL){
                // printf("2");
                if ((cur->next->pos - cur->pos) % 2 == 1) {
                    // printf("d\n");
                    first = cur-> next;
                } else {
                    count++;
                    // printf("\n");
                }
            } else if (cur->next == NULL){
                // printf("3");
                if ((cur->pos - prev->pos) % 2 == 0){
                    // printf("d\n");
                    prev->next = NULL;
                } else {
                    count++;
                    // printf("\n");
                }
            } else {
                // printf("4\n");
                if (((cur->next->pos - cur->pos) % 2 == 1) || ((cur->pos - prev->pos) % 2 == 0))
                    prev->next = cur->next;
                else
                    count++;
            }
            prev = cur;
            cur = cur->next;
        }
    }

    printf("%ld\n", ((uint64_t)(first - positions)) + 1);

    return EXIT_SUCCESS;
}

Test 1

Verdict: RUNTIME ERROR

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: WRONG ANSWER

Test 17

Verdict: WRONG ANSWER

Test 18

Verdict: WRONG ANSWER

Test 19

Verdict: WRONG ANSWER

Test 20

Verdict: WRONG ANSWER

Test 21

Verdict: WRONG ANSWER

Test 22

Verdict: ACCEPTED

Test 23

Verdict: WRONG ANSWER

Test 24

Verdict: WRONG ANSWER

Test 25

Verdict: WRONG ANSWER

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: WRONG ANSWER

Test 29

Verdict: ACCEPTED

Test 30

Verdict: WRONG ANSWER

Test 31

Verdict: ACCEPTED

Test 32

Verdict: ACCEPTED

Test 33

Verdict: ACCEPTED

Test 34

Verdict: WRONG ANSWER

Test 35

Verdict: WRONG ANSWER

Test 36

Verdict: WRONG ANSWER

Test 37

Verdict: WRONG ANSWER

Test 38

Verdict: ACCEPTED

Test 39

Verdict: WRONG ANSWER

Test 40

Verdict: WRONG ANSWER

Test 41

Verdict: WRONG ANSWER

Test 42

Verdict: WRONG ANSWER

Test 43

Verdict: WRONG ANSWER

Test 44

Verdict: WRONG ANSWER

Test 45

Verdict: WRONG ANSWER

Test 46

Verdict: ACCEPTED

Test 47

Verdict: WRONG ANSWER

Test 48

Verdict: ACCEPTED

Test 49

Verdict: WRONG ANSWER

Test 50

Verdict: WRONG ANSWER

Test 51

Verdict: WRONG ANSWER

Test 52

Verdict: WRONG ANSWER

Test 53

Verdict: ACCEPTED

Test 54

Verdict: WRONG ANSWER

Test 55

Verdict: WRONG ANSWER

Test 56

Verdict: WRONG ANSWER

Test 57

Verdict: WRONG ANSWER

Test 58

Verdict: WRONG ANSWER

Test 59

Verdict: WRONG ANSWER

Test 60

Verdict: WRONG ANSWER

Test 61

Verdict: WRONG ANSWER

Test 62

Verdict: WRONG ANSWER

Test 63

Verdict: WRONG ANSWER

Test 64

Verdict: WRONG ANSWER

Test 65

Verdict: WRONG ANSWER

Test 66

Verdict: WRONG ANSWER

Test 67

Verdict: WRONG ANSWER

Test 68

Verdict: WRONG ANSWER

Test 69

Verdict: WRONG ANSWER

Test 70

Verdict: WRONG ANSWER

Test 71

Verdict: WRONG ANSWER

Test 72

Verdict: WRONG ANSWER

Test 73

Verdict: WRONG ANSWER

Test 74

Verdict: WRONG ANSWER

Test 75

Verdict: WRONG ANSWER

Test 76

Verdict: WRONG ANSWER

Test 77

Verdict: WRONG ANSWER

Test 78

Verdict: WRONG ANSWER

Test 79

Verdict: WRONG ANSWER

Test 80

Verdict: WRONG ANSWER

Test 81

Verdict: WRONG ANSWER

Test 82

Verdict: WRONG ANSWER

Test 83

Verdict: WRONG ANSWER

Test 84

Verdict: WRONG ANSWER

Test 85

Verdict: WRONG ANSWER

Test 86

Verdict: WRONG ANSWER

Test 87

Verdict: WRONG ANSWER

Test 88

Verdict: WRONG ANSWER

Test 89

Verdict: WRONG ANSWER