Yokogawa R D Engineer interview questions

One room, one hour session. They gave me a topic, and asked me to write down code on papers to solve the topic's problem. During the session, no one is around but I think there is hidden camera somewhere. After I finished the code, the people came back and started to ask me why I wrote down those code. After explanation, they told me I can go back. And I was told I passed within one week. The second round interview was formal talks, no technical things.