Frequencies

L2 Easy Arrays & Hashing

Concept

A frequency dictionary maps each value to how many times it occurred. The default: subscript makes tallying a one-liner.

Return a dictionary that maps each distinct integer in nums to the number of times it appears.

Examples

▸ nums = [1, 2, 1, 3]

→ {1: 2, 2: 1, 3: 1}

▸ nums = []

→ {}

▸ nums = [7]

→ {7: 1}

Progressive Hints

Hint 1 · Nudge

For every distinct number, answer one question: how often did it show up?

Hint 2 · Plan

Create an empty map. For each number, add 1 to its entry, starting a new entry at 0 if the number hasn't been seen yet. Return the filled map.

Hint 3 · Approach

counts = empty map. For each n: counts[n] = counts.getOrDefault(n, 0) + 1. Return counts.

Output

// Run your code to see the output here.