Which is one reason why the purely clever approach is weak. The hero walks in, produces a document, and proves that the charges made by the king founder on a legal loophole. Flat and anticlimatic. Even for a comic story. Feasible only for a short one, where there's not enough build-up to disappoint us too much.
The brute force one is just as bad. If the hero walks into the throne room and lops off the king's head like that, the story wastes all its build up on anticlimax, to the mutters of why didn't he, or someone, do that along time ago? Even -- perhaps especially -- if getting to the throne room was hard, hard, hard.
Now, if the hero was chased into the throne room by the guards, or if there were traps of magic in the throne room and the king's sly threats and promises as he worked his way to the throne -- that could work.
On the whole, I think that a good climax generally requires a level of force (brute or otherwise) that the hero finds difficult to sustain but manages to rally himself for, some cleverness on the heroic side, and preferably a moral component: the hero wins because the villain alienated his allies, and the hero won them over.,