Below is a pattern-focused set of foundational interval problems. These cover all key concepts you need for interviews:

• sorting + merging
• overlap detection
• scheduling
• heap + intervals
• greedy decisions
• line sweep

1. Merge Intervals (Core Foundation)

Core Skill

• Sort by start
• Merge overlapping ranges

Problems

• Merge Intervals
• Insert Interval

Pattern

intervals.sort(key=lambda x: x[0])

for start, end in intervals:
    if not merged or merged[-1][1] < start:
        merged.append([start, end])
    else:
        merged[-1][1] = max(merged[-1][1], end)

Key Insight

• Always sort first
• Compare with last merged interval