MEDIUM Greedy
452. Minimum Number of Arrows to Burst Balloons
📖 Problem
There are some spherical balloons taped onto a flat wall that represents the XY-plane. The balloons are represented as a 2D integer array points where points[i] = [xstart, ystart, xend, yend] denotes a balloon whose horizontal diameter stretches between xstart and xend and vertical diameter stretches between ystart and yend. An arrow can be shot at exactly xstart if ystart <= y <= yend along the path the arrow travels. No two arrow travel along exactly the same path. Return the minimum number of arrows that must be shot to burst all balloons.
🧠 Visual Learning Aid
1 Model the input into the right structure
2 Choose the core technique and invariant
3 Execute step-by-step with a sample
4 Validate complexity and edge cases
JS/TS Refreshers
- •Array methods (`push`, `pop`, `shift`, `slice`)
- •Object/Map/Set usage patterns
- •Function parameter and return typing
Logical Thinking Concepts
- •Define invariants before coding
- •Check edge cases first (`[]`, single element, duplicates)
- •Estimate time/space before implementation
- •Apply Greedy reasoning pattern
💡 Approach
- → Sort balloons by end coordinate
- → Count overlapping intervals greedily
- → If current balloon starts after previous ends, need new arrow
- → Time: O(n log n), Space: O(1)
🧭 Prerequisites
🛠️ Hints & Pitfalls
Hints
- •Sort balloons by end coordinate
- •Count overlapping intervals greedily
- •If current balloon starts after previous ends, need new arrow
Common Pitfalls
- •Time: O(n log n), Space: O(1)
🧪 Test Cases
Hidden tests on submit: 1
Test Case 1
Not run Input:
findMinArrowShots([[10,16],[2,8],[1,6],[7,12]]); Expected:
2 Test Case 2
Not run Input:
findMinArrowShots([[1,2],[3,4],[5,6],[7,8]]); Expected:
4 Test Case 3
Not run Input:
findMinArrowShots([[1,2],[2,3],[3,4],[4,5]]); Expected:
2 📝 Code Editor
📤 Output