triploblastic's blog

codeforces round #226 prob C
By triploblastic, 13 years ago, In English

can someone tell me what is wrong with my code? i first generated all the primes up to sqrt(10^7) and then for every prime, counted how many number are divided by it...

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13 years ago, hide # |
 
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First mistake is that MAX is too small

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13 years ago, hide # |
 
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while(X[i] % prime[j] == 0)
      X[i] /= prime[j];

I do not understand why you do it. You just need to determine whether X[i] is divisible by prime[j] but not the power of prime[j] in X[i]

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    13 years ago, hide # ^ |
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     while(j < prime.SZ) {
      if(X[i] < prime[j])
        break;
      if(X[i] % prime[j] == 0) {
        prime_cnt[j]++;
        while(X[i] % prime[j] == 0)
          X[i] /= prime[j];
      }

      j++;
    }

    also need to reduce x[i],and reduce "while" working time,but it is not enough to passed

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      13 years ago, hide # ^ |
       
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      i figured this inner loop will run 20 times max for each X[i] cause 2^20 ~ 10^7, the limit for each number...so this should be 10^6 * 20 ~ 2*10^7... but i cant figure out why did it get WA in #test case 6..

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        13 years ago, hide # ^ |
         
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        You should use primes bigger than sqrt(10^7) too. Why did you just get rid of them?

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13 years ago, hide # |
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wrong post place

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