Lukujono

#include <stdio.h>

int main(void) {
    int X;
    if (scanf("%d", &X) != 1) {
        return 1;
    }

    while (X != 1) {
        printf("%d ", X);
        if (X % 2 == 0) {
            X = X / 2;
        } else {
            X = 3*X + 1;
        }
    }
    printf("1\n");
    return 0;
}

Test 1 (public)

Verdict: WRONG ANSWER