Detect Circular Pattern Match

Code

#include <stdio.h>
#include <stdint.h>

#include <stdint.h>

uint8_t is_circular_match(uint16_t reg, uint16_t target) {
    uint8_t res = 0;
    for (int i = 0; i < 16; i++) {
        // circular left rotate by i, avoiding undefined shift when i=0
        uint16_t rot = (uint16_t)((reg << i) | (reg >> ((16 - i) & 15)));
        res |= (rot == target);   // 0 or 1, no if
    }
    return res; // 1 if any rotation matched, else 0
}

int main() {
    uint16_t reg, target;
    scanf("%hu %hu", &reg, &target);
    printf("%hhu", is_circular_match(reg, target));
    return 0;
}

Solving Approach