Detect Alternating Pattern

Code

#include <stdio.h>

int is_alternating_pattern(int *mem, int k) {
    if (k <= 1) return 1;   // length 0 or 1 is trivially alternating

    int *p = mem;           // points to element 0
    int *q = mem + 1;       // points to element 1
    int checked = 1;        // we have already positioned q at index 1

    while (checked < k) {
        if (*p == *q) {     // adjacent equal -> not alternating
            return 0;
        }
        p++; q++;           // advance both pointers by one element
        checked++;
    }

    return 1;               // all checked pairs were alternating
}

int main() {
    int n, k, arr[100];
    if (scanf("%d %d", &n, &k) != 2) return 0;
    for (int i = 0; i < n; i++) scanf("%d", &arr[i]);

    // assume k is <= n as per problem statement; otherwise we could clamp/check
    int res = is_alternating_pattern(arr, k);
    printf("%d", res);
    return 0;
}

Solving Approach