Create dp1.java

[Praniksha123]

No description provided.

[super30admin]

Coin Change (dp1.java)

Great work! Your solution correctly solves the Coin Change problem using bottom-up dynamic programming. Here are some observations:

Strengths:

1. Your DP approach is correct and handles all edge cases properly
2. The use of amount+1 as a sentinel value is a clever way to handle the impossible case
3. The recurrence relation is correctly implemented
4. Your solution is more efficient than the reference solution (O(n*m) vs O(2^(m+n)))

Areas for Improvement:

1. Space Optimization: Your solution uses O(n*m) space. You can optimize this to O(m) space using a 1D DP array:

   int[] dp = new int[amount + 1];
   Arrays.fill(dp, amount + 1);
   dp[0] = 0;
   for (int coin : coins) {
       for (int j = coin; j <= amount; j++) {
           dp[j] = Math.min(dp[j], dp[j - coin] + 1);
       }
   }
   return dp[amount] > amount ? -1 : dp[amount];

2. Code Organization: The file contains two unrelated solutions (Coin Change and House Robber). Consider separating them into different files for better organization.

3. Variable Naming: Consider using more descriptive variable names like numCoins instead of n and targetAmount instead of m for better readability.

Overall, your solution is correct and efficient. The main improvement would be the space optimization.

VERDICT: PASS

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House Robber

Excellent work! Your solution demonstrates a strong understanding of dynamic programming and space optimization. Here are some specific points:

Strengths:

1. Optimal Space Complexity: By using only two variables instead of a DP array, you've achieved O(1) space complexity, which is the best possible for this problem.
2. Clean Implementation: The code is concise and easy to follow.
3. Proper Base Case Handling: You correctly handle the edge case of a single house.
4. Better than Reference: Your solution is asymptotically better than the reference solution in both time and space.

Areas for Improvement:

1. File Organization: The file contains two separate solutions (coinChange and rob). While this isn't incorrect, it's better practice to have one solution per file/class for clarity.
2. Variable Naming: Consider using more descriptive names like prevMax and currMax instead of prev and curr for better readability.
3. Comments: Adding brief comments explaining the DP recurrence would help others understand your approach.

Overall: This is a textbook optimal solution that demonstrates mastery of the problem. Well done!

VERDICT: PASS