SproutStack🌱 DSA (Beginner) · Next Level (Brief) · cozy lesson
Matrix BFS: Rotting Oranges 🔒 premium preview
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11 min · 1 min read · no scary math, promise
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You’ve got this. Read a little, play a little — I’ll wait. No rush.
from collections import deque
def oranges(g):
q = deque([(r,c) for r in range(len(g)) for c in range(len(g[0])) if g[r][c]==2])
mins, fresh = 0, sum(v==1 for row in g for v in row)
# standard level BFS...
return mins if fresh==0 else -1
Pattern: walls-and-gates, shortest bridge — same multi-source idea.
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Check your understanding
Correct answers earn XP (once each).
1. Start BFS from…
2. Fresh left at end?
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