题解常用的英文表达

One interesting observation is that ...

This solution works in \(O(N)\) time.

viable/feasible 可行的、合法的

The given condition can be rephrased as follows: ...

By doing ..., we can restate the condition of the problem as follows: ...

... could be rephrased to say that ...

Now that we know sth. is unique, we can give it a notation.

The key observation in this problem is that ... The other observation we need is that ... These two observations lead us to a ... solution.