Completed DFS-1

[sandeepkumarks]

No description provided.

[super30admin]

Coin Change (CoinChange.java)

Strengths:

• Correct implementation of bottom-up DP
• Good use of sentinel value (amount + 1) to represent infinity
• Clear comments explaining the approach
• Well-structured and readable code
• Significantly better time complexity than the reference solution

Areas for improvement:

• Consider optimizing space complexity to O(amount) using a 1D DP array. The recurrence dp[i][j] = min(dp[i-1][j], dp[i][j - coins[i-1]] + 1) only depends on the current row and the same row at a smaller column, so you can reuse a single array.
• The variable name coins[i - 1] is used multiple times - extracting it to a local variable could improve readability slightly.

VERDICT: PASS

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House Robber (HouseRobber.java)

Great work on your solution! Your dynamic programming approach is correct and significantly more efficient than the recursive approach in the reference solution. Here are some observations:

Strengths:

1. Optimal Time Complexity: Your O(n) solution is much better than the reference's O(2^n) approach.
2. Clear Comments: Your comments effectively explain the DP approach and recurrence relation.
3. Edge Case Handling: You correctly handle the case when there's only one house.
4. Clean Code: The code is readable and well-organized.

Areas for Improvement:

1. Space Optimization: You could reduce space complexity from O(n) to O(1) by using just two variables to track the previous two DP values:

   class Solution {
       public int rob(int[] nums) {
           if(nums.length == 1) return nums[0];
           int prev2 = nums[0];
           int prev1 = Math.max(nums[0], nums[1]);
           for(int i = 2; i < nums.length; i++) {
               int curr = Math.max(prev1, nums[i] + prev2);
               prev2 = prev1;
               prev1 = curr;
           }
           return prev1;
       }
   }

2. Variable Naming: Consider using more descriptive variable names like rob instead of dp to better convey the meaning.

Overall, this is an excellent solution that demonstrates strong understanding of dynamic programming!

VERDICT: PASS