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POSolve Number Puzzle with C and Java
 

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  1. POSolve Number Puzzle with C and Java
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    <p>This question is translated into English by me from another forum, I found it interesting and then just write a Java solution. And found there's some heap size problem when dealing with large number like 10000000. And I would like to seek some really smart solution compared with my own.</p> <p>Original Post is in Chinese. And I kind of revised it a little based on my understanding to make it clearer. <a href="http://zhidao.baidu.com/question/1637660984282265740.html?sort=6&amp;old=1#here" rel="nofollow">http://zhidao.baidu.com/question/1637660984282265740.html?sort=6&amp;old=1#here</a></p> <p>Below is the puzzle:</p> <pre><code>10000 rows of numbers; 1 row: 2,4,6,8...2K(2K&lt;=10000000); (numbers no repeats for this row) 2 row: 3,3,6,6,9,9...3K(3K&lt;=10000000); (starting from this row, each number repeats 2 times and a multiple which has something to do with row number (2XrowNumber-1) to be specificaly) 3 row: 5,5,10,10,15,15...5K(5K&lt;=10000000); and following 7K,9K,11K,13K....until 10000 row: 19999,19999,39998,39998....19999K,19999K (19999K&lt;=10000000); </code></pre> <p>That's all the rows to be used in the following part. And now we will calculate the repeat times of numbers starting from row 1 and row 2:</p> <p>Integer w1 is the repeat times of numbers in row 1 and row2. For example, consider row 1 numbers 2,4,6 and row 2 numbers 3,3,6,6. Then the repeat times up to this point would be 3 since 6 is already in row 1 and appears 2 times in row 2, and 3 appears 2 times in row 2; </p> <pre><code>Integer w2 is the repeat times of numbers in row 1 and row 2 and row 3. Integer w3 is the repeat times of numbers in row 1 and row 2 and row 3 and row 4. ...... Integer w9999 is the repeat times of numbers of row 1,row 2,row 3 .....row 10000. </code></pre> <p>And now print out all integers, w1,w2....w9999;</p> <p>I have come up with one Java solution, but I have heap size problem since 10000000 is too large and the memory is not enough. So I just use 10000 instead of 10000000, and 10 instead of 10000. Below is what I write in Java. I guess it should be right (if not, please point it out):</p> <pre><code> Set nums = new HashSet(); int max = 10000; int row = 10; for (int i=2;i&lt;=max;i+=2){ nums.add(new Integer(i)); } int nums_size = nums.size(); int w = 0; for (int i=2;i&lt;=(row);i++){ int tmp_count = 0; int self_count = 0; for (int j=(2*i-1);j&lt;=max;j+=(2*i-1)){ nums.add(new Integer(j)); self_count++; if (nums.size()==nums_size){ tmp_count++; } else { nums_size = nums.size(); } } w += tmp_count; w += self_count; System.out.println("w"+(i-1)+": "+w); } </code></pre> <p>My question is </p> <ol> <li>How to get a better solution in Java (if any)? </li> <li>How to do it in C since there would be no Set class in C as I remember. (importing 3rd party library would not be preferred)?</li> </ol> <p>Thanks.</p>
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    1. COI am surprised people already give down vote and not even tell me why?
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    2. COThis is stupid why was this downvoted - maybe someone did not know the answer.
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    3. COIs there a pattern for the numbers in each row?
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      1. POSolve Number Puzzle with C and Java
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