Min Arrows to Burst Balloons | Earliest End Wins | LeetCode 75 #73
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Min Arrows to Burst Balloons | Earliest End Wins | LeetCode 75 #73
5 просмотров · 7 дней назад
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5 просмотров · 7 дней назад
Minimum Number of Arrows to Burst Balloons (LeetCode 452) — the greedy interval classic every interviewer loves.
One arrow shot vertically bursts every balloon whose x-range contains the shot point. What is the FEWEST arrows needed? The answer: sort by END time, shoot each arrow at the earliest end, skip every balloon it bursts.
In this video (Hindi narration, English on screen):
The carnival intuition: one arrow, many balloons — why the earliest END picks the shot
The EXCHANGE ARGUMENT, made visual: slide any optimal first arrow to the earliest end and nothing escapes
Why the shot goes exactly AT the end, not the middle — the sliding-arrow demo with live burst counts
The tricky code line: why the overlap test uses STRICTLY greater than arrowX (the touching-endpoint trap [1,2],[2,3] needs just 1 arrow)
The comparator lambda (compare a[1] less than b[1]) and why sorting by start is flat-out WRONG (animated counter-example)
Full C++ code walkthrough, debugger-style: every line lights up as the visual mutates, with the WHY behind each line
4 classic bugs with test cases: greater-or-equal vs strictly-greater, start-sort, missed arrowX update, arrows = 0
Correctness proof in plain words + O(n log n) time / O(1) space analysis
6 edge cases: single, disjoint, all-overlap, touching chain, nested, negatives
Problem: https://leetcode.com/problems/minimum...
This is video #73 of the LeetCode 75 series in Hindi — 3D-animated, beginner-friendly, one problem at a time.
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