hash maps
strength 0 · 0/70 startedmap fundamentals0/6 skills started, includes your next skill
Create a hash mapUndiscovered, strength 0 of 100, recommended nextnext
Understand key versus valueUndiscovered, strength 0 of 100
Handle an empty hash mapUndiscovered, strength 0 of 100
Distinguish a map from a setUndiscovered, strength 0 of 100
Count entries in a hash mapUndiscovered, strength 0 of 100
Build a hash map from pairsUndiscovered, strength 0 of 100
put0/5 skills started
Put a key-value pairUndiscovered, strength 0 of 100
Put into an empty mapUndiscovered, strength 0 of 100
Overwrite the value for a keyUndiscovered, strength 0 of 100
Put several pairsUndiscovered, strength 0 of 100
Why map put is expected O(1)Undiscovered, strength 0 of 100
get0/5 skills started
Get the value for a keyUndiscovered, strength 0 of 100
Undiscovered · strength 0/100 · not practised yet
You haven't encountered this yet.
- Two Sumeasy
Miss a map keyUndiscovered, strength 0 of 100
Get is not a search by valueUndiscovered, strength 0 of 100
Supply a default for a missing keyUndiscovered, strength 0 of 100
Distinguish a missing key from value zeroUndiscovered, strength 0 of 100
contains key0/4 skills started
Check whether a map contains a keyUndiscovered, strength 0 of 100
Undiscovered · strength 0/100 · not practised yet
You haven't encountered this yet.
- Two Sumeasy
Contains-key versus contains-valueUndiscovered, strength 0 of 100
Keys are unique values need not beUndiscovered, strength 0 of 100
Test has-key before getUndiscovered, strength 0 of 100
map delete0/4 skills started
Remove a key from a mapUndiscovered, strength 0 of 100
Remove a missing map keyUndiscovered, strength 0 of 100
Remove the last map entryUndiscovered, strength 0 of 100
Why map delete is expected O(1)Undiscovered, strength 0 of 100
frequency maps0/5 skills started
Build a frequency mapUndiscovered, strength 0 of 100
Undiscovered · strength 0/100 · not practised yet
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- Valid Anagrameasy
- Group Anagramsmedium
Increment the count for a keyUndiscovered, strength 0 of 100
Decrement a count and maybe removeUndiscovered, strength 0 of 100
Find the most frequent keyUndiscovered, strength 0 of 100
Compare two frequency mapsUndiscovered, strength 0 of 100
Undiscovered · strength 0/100 · not practised yet
You haven't encountered this yet.
- Valid Anagrameasy
grouping0/4 skills started
Group values by a keyUndiscovered, strength 0 of 100
Undiscovered · strength 0/100 · not practised yet
You haven't encountered this yet.
- Group Anagramsmedium
Group indices per valueUndiscovered, strength 0 of 100
Append to a list under a keyUndiscovered, strength 0 of 100
Undiscovered · strength 0/100 · not practised yet
You haven't encountered this yet.
- Group Anagramsmedium
Overwrite is the grouping bugUndiscovered, strength 0 of 100
index maps0/4 skills started
Map a value to its first indexUndiscovered, strength 0 of 100
Map a value to its last indexUndiscovered, strength 0 of 100
Two-sum with a value-to-index mapUndiscovered, strength 0 of 100
Undiscovered · strength 0/100 · not practised yet
You haven't encountered this yet.
- Two Sumeasy
Pick an index map when position mattersUndiscovered, strength 0 of 100
updating values0/4 skills started
Update a map value in placeUndiscovered, strength 0 of 100
Put if the key is absentUndiscovered, strength 0 of 100
Merge two mapsUndiscovered, strength 0 of 100
Compute a value from the previousUndiscovered, strength 0 of 100
map iteration0/4 skills started
Iterate the keys of a mapUndiscovered, strength 0 of 100
Iterate the values of a mapUndiscovered, strength 0 of 100
Iterate key-value pairsUndiscovered, strength 0 of 100
Do not assume map iteration orderUndiscovered, strength 0 of 100
map hashing0/4 skills started
Hash a map key to a bucketUndiscovered, strength 0 of 100
Collision chains store pairsUndiscovered, strength 0 of 100
Map keys must be immutableUndiscovered, strength 0 of 100
Expected O(1) map get versus worst O(n)Undiscovered, strength 0 of 100
when not a map0/4 skills started
Membership only is a setUndiscovered, strength 0 of 100
Tiny alphabet is an arrayUndiscovered, strength 0 of 100
Pick a tree map when keys must stay sortedUndiscovered, strength 0 of 100
Values without keys is a listUndiscovered, strength 0 of 100
nested and pair keys0/4 skills started
Store a map of mapsUndiscovered, strength 0 of 100
Pair keys need a compositeUndiscovered, strength 0 of 100
Serialize a pair as a keyUndiscovered, strength 0 of 100
Nested get with a missing inner mapUndiscovered, strength 0 of 100
copy and compare maps0/4 skills started
Copy a hash mapUndiscovered, strength 0 of 100
Compare two hash mapsUndiscovered, strength 0 of 100
Map equality is key and valueUndiscovered, strength 0 of 100
Prove a map copy does not share storageUndiscovered, strength 0 of 100
complexity for maps0/4 skills started
Recognize expected O(1) map getUndiscovered, strength 0 of 100
Extra space of a hash mapUndiscovered, strength 0 of 100
Build a map in linear timeUndiscovered, strength 0 of 100
Nested scan versus a mapUndiscovered, strength 0 of 100
problem decomposition for maps0/5 skills started
Recognize a key-value queryUndiscovered, strength 0 of 100
Recognize a frequency queryUndiscovered, strength 0 of 100
Decide map versus setUndiscovered, strength 0 of 100
Decide map versus array tableUndiscovered, strength 0 of 100
Draw the map after each operationUndiscovered, strength 0 of 100