Mutual Translation Routes

Problem

Table: `route`

| Column Name | Type |
|---|---|
| src | int |
| dst | int |

This table may contain duplicate rows and has no primary key. Each row records that a translation memory exists from language code `src` to language code `dst`.

A route is *mutual* when a reverse route also exists: for a row `(src, dst)` there is a different row `(src2, dst2)` with `src = dst2` and `dst = src2`. Find every mutual pair and report it once in normalized form where `src <= dst`. Return columns `src` and `dst`, ordered by `src`, then `dst`.

Tables

Example rows — the live problem includes the full dataset.

Expected output

Your answer should return 2 rows with the columns src, dst.

Starter code (SQL)

SELECT *
FROM route;

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