Mandarin has an unambiguous simplex 不 bù which means ‘no’ on its own, but no equivalent simplex that means ‘yes’.
不 does double duty as the negating particle for non-past verbs, so it’s not only used as a standalone ‘no’, but it is used thus. With past verbs (i.e., with the perfective-like particle 了 le), the negator is instead 没(有) méi(yǒu), which is also used to reply in the negative; as a reply, the second syllable/character is never omitted.
When commenting or answering questions in the affirmative, it is most common to use 对 duì ‘correct’, or in some cases to repeat the verb, especially if the verb is a ‘core’ verb like 是 shì ‘be [copular]’, 在 zài ‘be [located]’, 有 yǒu ‘have’, modal verbs, etc. Repeating the verb, negated, can of course also be used for negative replies.
There is an affirmative grunt, often written 嗯 ǹ(g), èn(g) (but commonly pronounced [ɔ˦˨ ~ ɔ˧]), which is similar to ‘uh-huh’ in English, but that’s not really a lexeme as such, and like its English equivalent, it is used more on its own to encourage the speaker to continue than to give an actual affirmative reply.
In 1996, a famous Chinese manifesto was published entitled China Can Say No or The China That Can Say No. Its Chinese title is 中国可以说不 Zhōngguó kěyǐ shuō bù, showing that 不 works as an abstract nominal form of expressing a negative reaction, like English ‘no’.
The manifesto was in turn based on a Japanese essay from 1989 entitled The Japan That Can Say No with similar goals and contents. The Japanese title of this essay, 「NO」と言える日本 ‘NO’ to ieru Nihon, is interesting because it shows that the Japanese word for no, いいえ īe, does not work in the same way, using instead the English word. (This is also because the essay is critic of and wants Japan to distance itself from the US, but いいえ would not have worked as well in the context.)
If the titles had been reversed, Mandarin also would not really have had a straightforward way to express things. Beyond using the affirmative grunt or a semantically different verb like 同意 tóngyì ‘agree’, there isn’t really an obvious way to say, “China can say yes”.