Organizing semaphores into a pyramid

My homework was to organize semaphores into a pyramid. The task was accomplished, but I ended up with this long ugly conditional and was wondering if anyone can see a better way/algorithm to accomplish the same thing.

if (me==0) {
    wait_sem(semaphore[1]);
    wait_sem(semaphore[2]);
    signal_sem(semaphore[0]);

}

if (me==1) {
    wait_sem(semaphore[3]);
    wait_sem(semaphore[4]);

}
if (me==2) {
    wait_sem(semaphore[4]);
    wait_sem(semaphore[5]);

}

if (me==3) {
    wait_sem(semaphore[6]);
    wait_sem(semaphore[7]);

}
if (me==4) {
    wait_sem(semaphore[7]);
    wait_sem(semaphore[8]);

}
if (me==5) {
    wait_sem(semaphore[8]);
    wait_sem(semaphore[9]);

}
if (me==6) {
    wait_sem(semaphore[10]);
    wait_sem(semaphore[11]);

}
if (me==7) {
    wait_sem(semaphore[11]);
    wait_sem(semaphore[12]);

}
if (me==8) {
    wait_sem(semaphore[12]);
    wait_sem(semaphore[13]);

}

if (me==9) {
    wait_sem(semaphore[13]);
    wait_sem(semaphore[14]);

}

I wouldn't even use a switch here:

wait_sem(semaphore[me*2+1]);
wait_sem(semaphore[me*2+2]);
if (me==0) {
    signal_sem(semaphore[0]);    
}

Edit: I see the sequence is not quite linear. If you can come up with an easy mapping between me and the indices, this will work (but with a different formula). Otherwise, a switch statement may be the easiest way.

You can also bury the switch inside a map by mapping the input ints to the two indices (std::map >). It essentially does the same thing, but you can hide the ugly in a header file.

StackExchange Code Review Q#33626, answer score: 4