John W. Hinckley, Jr., who is accused of shooting President Reagan and three others here last March 30, says Reagan "is the best president we've had this century" and that politics "has nothing to do with political assassinations in America."

In a written response to a series of questions submitted to him by Newsweek magazine and scheduled for publication in Newsweek editions appearing tomorrow, the imprisoned Hinckley also said he favors gun control and has idolized only one person in his life: Beatles singer John Lennon.

Lennon was shot and killed in New York last Dec. 8 by 25-year-old Mark David Chapman. Chapman has pleaded not guilty by reason of insanity in the shooting.

Hinckley, 26, who is being held at the Army stockade at Fort Meade, Md., also plans to claim he was insane at the time of the shooting of Reagan and should not be held criminally responsible for his acts, according to his attorneys.

In his hand-written response to 20 Newsweek questions, Hinckley said he believes President Reagan's tax cut and military buildup policies will help Americans, and "he is the best president we've had this century. Let's give him a chance."

He said he does not admire any political leaders, "except perhaps Mr. Reagan. The only person I ever idolized . . . was John Lennon, and look what happened to him."

Asked if he thinks there is a pattern of personalities among people who attack political figures, Hinckley said "Most assassins are disillusioned with everything, most of all politics. The ideology of the target doesn't matter. Politics has nothing to do with political assassinations in America."

On gun control, Hinckley said guns "cannot be banned or eliminated, but some stricter laws could be applied when buying a handgun."

Hinckley wrote Newsweek Sept. 3, offering to answer 20 questions not dealing directly with the Reagan shooting. He has written to other news organs, including a letter dated Sept. 7 to a Washington Post reporter in which he said he traveled extensively before the Reagan shooting to be near actress Jodie Foster. Law enforcement officials believe Hinckley tried to kill Reagan to impress Foster.