Combination Sum 25 XP Medium

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Find all unique combinations of candidates that sum to target. The same number can be used unlimited times.

candidates = [2, 3, 6, 7], target = 7
# [2, 2, 3] and [7] → 2 combinations

Backtracking: at each step, either take the current candidate again (pass same index) or move to the next candidate.

💡 Pro tip: Understand this problem deeply — don't just memorize the code. Try explaining the approach out loud as if teaching a friend. If you can explain it simply, you truly understand it!

📋 Instructions

Find all combinations summing to 7 from [2,3,6,7]. Print the count.

Backtrack(start, path, remaining). If remaining==0, add path. For each candidate from start, if candidate <= remaining, recurse.

🧪 Test Cases

Input

len(combinationSum([2,3,6,7], 7))

Expected

2

Test case 1

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main.py

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Output

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