Greedy Algorithms - Jump Game (Can Reach End?)
Given the memoization cache state after processing input array of length 5: memo = [True, True, False, None, None], which of the following input arrays could produce this memo state?
Given the memoization cache state after processing input array of length 5: memo = [True, True, False, None, None], which of the following input arrays could produce this memo state?
hard🔄 Reverse Engineer Q9 of Q15
Step-by-Step Solution
Solution:
Step 1: Interpret memo values
memo[0]=True means start reachable; memo[2]=False means position 2 cannot reach end.Step 2: Check input arrays
[3,2,1,0,4] allows jump over 0 at pos 3, so memo[2] likely True; [2,3,1,0,4] matches memo pattern with stuck at pos 2.Final Answer:
Option A -> Option AQuick Check:
Only [2,3,1,0,4] matches memo with False at pos 2 [OK]
Quick Trick: False in memo means stuck position in input [OK]
Common Mistakes:
MISTAKES- Ignoring memo meaning
- Assuming all True memo
Trap Explanation:
PITFALL- Candidates confuse memo meaning or pick input with no stuck positions.
Interviewer Note:
CONTEXT- Tests ability to reason backward from DP memo to input.
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