60. Detect Alternating Pattern

#include <stdio.h>

int is_alternating_pattern(int *mem, int k) {
    // check if enough elements for an alternating pattern
    if (k < 2) 
        return 0;

    // init with first 2 elements
    int pattern1 = *mem++;
    int pattern2 = *mem++;

    // check if already pattern not alternating
    if (pattern1 == pattern2)
        return 0;

    // check if remaining elements follow the pattern
    for (int i = 2; i < k; i++) {
        int current = *mem++;
        if ((i % 2) == 0 && current != pattern1) {
            // even index -> should have followed pattern1
            return 0;
        }
        if ((i % 2) != 0 && current != pattern2) {
            // odd index -> should have followed pattern2
            return 0;
        }
    }
    return 1;
}

int main() {
    int n, k, arr[100];
    scanf("%d %d", &n, &k);

    for (int i = 0; i < n; i++) {
        scanf("%d", &arr[i]);
    }

    int res = is_alternating_pattern(arr, k);
    printf("%d", res);

    return 0;
}

Generic solution that works for any numbers, not only 0 and 1.