[Solved] The following code attempts to solve the Jump Game problem. Identify the line that contains a subtle bug... Identify the line that contains a subtle bug that causes incorrect results on some inputs. | Greedy Algorithms

Greedy Algorithms - Jump Game (Can Reach End?)

The following code attempts to solve the Jump Game problem. Identify the line that contains a subtle bug that causes incorrect results on some inputs.

def canJump(nums):
    maxReach = 0
    for i, jump in enumerate(nums):
        # Bug: missing check if current index is beyond maxReach
        maxReach = max(maxReach, i + jump)
        if maxReach >= len(nums) - 1:
            return True
    return False

ALine 2: Initialization of maxReach

BLine 3: for loop header enumerating nums

CLine 4: Missing check if i > maxReach before updating maxReach

DLine 6: Checking if maxReach reaches or exceeds last index

Step-by-Step Solution

Solution:

Step 1: Understand the missing condition
The code does not check if the current index i is beyond maxReach, which means it may continue even when stuck.
Step 2: Identify the bug line
Line 4 updates maxReach without verifying if i is reachable, causing false positives on inputs with unreachable indices.
Final Answer:
Option C -> Option C
Quick Check:
Adding "if i > maxReach: return False" fixes the bug [OK]

Quick Trick: Check if current index is reachable before updating maxReach [OK]

Common Mistakes:

MISTAKES

Forgetting to check i > maxReach
Assuming maxReach update alone suffices

Trap Explanation:

PITFALL

Without the check, code wrongly assumes progress is always possible, missing stuck cases.

Interviewer Note:

CONTEXT

Tests if candidate can spot subtle boundary condition bugs in greedy code.

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More Greedy Algorithms Quizzes

The following code attempts to solve the Jump Game problem. Identify the line that contains a subtle bug that causes incorrect results on some inputs.

Step 1: Understand the missing condition

Step 2: Identify the bug line

Final Answer:

Quick Check:

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