Details
For each set of three musical notes forming a triad, print the name of the chord they form, consisting of the root note and the type of triad.
Each note is represented as an uppercase letter, optionally followed by a single accidental, either sharp (♯ U+266F) or flat (♭ U+266D).
Background:
There are twelve pitch classes in twelve-tone equal temperament, some of which have multiple names due to ♯ and ♭ raising and lowering the pitch, respectively. They are, in ascending order:
| # | Name 1 | Name 2 |
|---|---|---|
| 0 | A | |
| 1 | A♯ | B♭ |
| 2 | B | C♭ |
| 3 | C | B♯ |
| 4 | C♯ | D♭ |
| 5 | D | |
| 6 | D♯ | E♭ |
| 7 | E | F♭ |
| 8 | F | E♯ |
| 9 | F♯ | G♭ |
| 10 | G | |
| 11 | G♯ | A♭ |
A triad consists of a root note on the bottom followed by two thirds stacked on top of it. Thirds describe the distance between the preceding and following note. A third can be either of two types:
| Name | Distance | Example |
|---|---|---|
| Minor third | 3 | A C (note 0 to note 3) |
| Major third | 4 | C E (note 3 to note 7) |
Being that there are 2 thirds in a triad and each third can be of 2 different types, there are 4 total “types” of triads. They are:
| Triad Name | Thirds (Bottom to Top) | Example |
|---|---|---|
| Diminished Triad | Minor, Minor | B D F |
| Minor Triad | Minor, Major | E G B |
| Major Triad | Major, Minor | C E G |
| Augmented Triad | Major, Major | D F♯ A♯ |
Input:
- Triads of notes will always be written out so that the letters in the name used ascend by 2 between each third (wrapping back to A after G). Therefore, a triad consisting of notes 3, 6, and 9 may be written as B♯ D♯ F♯ or C E♭ G♭, but not, for example, as C D♯ F♯.
- The notes may appear in any order, e.g., C E G and E C G both may appear.
Output:
- Chords are named by the root note followed by nothing for major, m for minor, ° U+00B0 for diminished, and + for augmented.
- The spelling of the root note in the output must match the input, e.g. the expected output for C E♭ G♭ is C°, not B♯°.
Note: to find the root, look only at the letters. E G♯ C and E G♯ B♯ cannot be told apart by a method that only considers note distances. The root is the note whose letter comes 2 and 4 letters before the other two letters in the chord. The expected outputs are C+ and E+ respectively.
External links: Wikipedia