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    <p>A quick google search returned <a href="http://www.careercup.com/question?id=2622" rel="nofollow">this</a>. In any case, if you're not looking for performance, <a href="http://en.wikipedia.org/wiki/Backtracking" rel="nofollow">backtracking</a> is always an option</p> <p>EDIT: I tried to apply backtracking. My solution is in no way efficient. You can, of course, replace the average methods to avoid another level of cycling. Also, in order to show that there is no solution, you can just count the number the solutions.</p> <pre><code>import java.util.ArrayList; import java.util.HashSet; import java.util.Iterator; import java.util.List; public class SOQuestion { /** * just prints a solution * * @param list * @param indexes */ public static void printSolution(List list, HashSet indexes) { Iterator iter = indexes.iterator(); while (iter.hasNext()) { System.out.print(list.get((Integer) iter.next()) + " "); } System.out.println(); } /** * calculates the average of a list, but only taking into account the values * of at the given indexes * * @param list * @param indexes * @return */ public static float avg(List list, HashSet indexes) { Iterator iter = indexes.iterator(); float sum = 0; while (iter.hasNext()) { sum += (Integer) list.get((Integer) iter.next()); } return sum / indexes.size(); } /** * calculates the average of a list, ignoring the values of at the given * indexes * * @param list * @param indexes * @return */ public static float avg_e(List list, HashSet indexes) { float sum = 0; for (int i = 0; i &lt; list.size(); i++) { if (!indexes.contains(i)) { sum += (Integer) list.get(i); } } return sum / (list.size() - indexes.size()); } public static void backtrack(List list, int start, HashSet indexes) { for (int i = start; i &lt; list.size(); i++) { indexes.add(i); if (avg(list, indexes) == avg_e(list, indexes)) { System.out.println("Solution found!"); printSolution(list, indexes); } backtrack(list, i + 1, indexes); indexes.remove(i); } } public static void main(String[] args) { List test = new ArrayList(); test.add(2); test.add(1); test.add(3); backtrack(test, 0, new HashSet()); } } </code></pre>
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    1. POhow to divide an integer array into 2 sub-arrays and make their averages equal?
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    1. POhow to divide an integer array into 2 sub-arrays and make their averages equal?
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    1. COI checked those.They are not accurate. Most of them are not correct
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    2. CO@drstupid: A good answer should be self-contained and complete (if possible). If you just have a link that you googled, make it a comment. Same for a single catchword (`backtracking`). To make this an answer, explain how to solve the problem, and post these links as references.
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    3. CO@stupid: I agree. Please be specific
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