UVA 1213 — Sum of Different Primes, Help !!

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UVA 1213 — Sum of Different Primes, Help !!

Revision en2, by approach, 2021-10-01 11:34:00

Problem Link so, I was able to come up with memoization approach, but unable to write iterative version.

The correct one happens to be

Correct implementation

vector<vector<int>> dp(16, vector<int>(1180, 0));
  
  dp[0][0] = 1;

  for (int i = 0; i < arePrimes.size(); i++)
    for (int k = 14; k >= 1; k--)
      for (int n = 1170; n >= arePrimes[i]; n--)
        dp[k][n] += dp[k - 1][n - arePrimes[i]];
  
  cout << dp[K][N] << '\n';

But I failed to realise, why this one is wrong.

wrong one

    vector<vector<int>> dp(16, vector<int>(1180, 0));

    dp[0][0] = 1;

    for (int i = 0; i < arePrimes.size(); i++)
      for (int k = 1; k <= 14; k++)
        for (int n = arePrimes[i]; n <= 1170; n++)
          dp[k][n] += dp[k - 1][n - arePrimes[i]];

    cout << dp[K][N] << '\n';

could u help me out please, any kind of help on how to approach such iterative DP problems, will be appreciated.

need help, uva, dp problem, iterative dp

History

Revisions

	Rev.	Lang.	By	When	Δ	Comment
	en2		approach	2021-10-01 11:34:00	7
	en1		approach	2021-10-01 11:22:35	1190	Initial revision (published)