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LeCalin's blog

Easy problem on DP
By LeCalin, history, 9 years ago, In English

Hello Codeforces .

Plase help.

Given n, array a(a1, a2,,, an). n, a[i] <= 100.

How can i make dp[i][j].

Corectly dp[i][j] = 1, if we can get sum j without a[i].

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9 years ago, hide # |
 
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How can you say its easy if you are stuck in it and asking for help? :/

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    9 years ago, hide # ^ |
     
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    it is easy for some people

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      9 years ago, hide # ^ |
       
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      I have thought of a solution.

      Take dpt[j] be the number of ways you can make the sum j using any elements. So, for each sum from 1 to 10000, you take each of the a[i] into consideration and do a dpt[sum-a[i]]++.

      Now, dp[i][j] is 1 if dpt[j]>=2 or else its 0.

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9 years ago, hide # |
 
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What are the constraints on n ?

If you don't mind, can you put a link to the exact question. This is kind of hard to understand.

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9 years ago, hide # |
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Calculate DP for prefixes and suffixes. Now, DP[i][j] = 1 if there exists A and B such that A+B=j and A is obtained as sum from prefix and B is obtained as sum from suffix.

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