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    copied!<p>I like the answer that mbeckish wrote but here is the code that I wrote to actually do the work:</p> <pre><code>import java.util.ArrayList; import java.util.List; public class Test { public static void main(String[] args) { List&lt;JobsInterval&gt; jobsIntervalList = new ArrayList&lt;JobsInterval&gt;(); jobsIntervalList.add(new JobsInterval(4, 1)); jobsIntervalList.add(new JobsInterval(1, 2)); jobsIntervalList.add(new JobsInterval(3, 2)); jobsIntervalList.add(new JobsInterval(0, 3)); jobsIntervalList.add(new JobsInterval(2, 3)); printPossibleCombinations(jobsIntervalList); } public static void printPossibleCombinations(List&lt;JobsInterval&gt; list) { //Assumes the list is already in interval order. int currentInterval = -1; List&lt;List&lt;JobsInterval&gt;&gt; outerList = new ArrayList&lt;List&lt;JobsInterval&gt;&gt;(list.size()); List&lt;JobsInterval&gt; innerList = null; //Loop through the list and group them into separate lists by interval. for (JobsInterval ji : list) { if (ji.interval != currentInterval) { if (null != innerList) outerList.add(innerList); currentInterval = ji.interval; innerList = new ArrayList&lt;JobsInterval&gt;(list.size()); } innerList.add(ji); } if (null != innerList) outerList.add(innerList); print(0, outerList, null); } public static void permute(StringBuilder value, List&lt;JobsInterval&gt; list, List&lt;String&gt; permutations) { //Check to see if this is the last recursive call if (0 == list.size()) { permutations.add(value.toString()); } else { List&lt;JobsInterval&gt; subList; for (int i = 0; i &lt; list.size(); i++) { subList = new ArrayList&lt;&gt;(list); subList.remove(i); permute(new StringBuilder(null == value ? "" : value).append(list.get(i).jobs), subList, permutations); } } } public static void print(int index, List&lt;List&lt;JobsInterval&gt;&gt; list, StringBuilder value) { //Check to see if this is the last recursive call if (list.size() == index) System.out.println(value.toString()); else { List&lt;JobsInterval&gt; intervalGroup = list.get(index); List&lt;String&gt; permutations = new ArrayList&lt;String&gt;(); permute(null, intervalGroup, permutations); for (String permutation : permutations) print(index+1, list, new StringBuilder(null == value ? "" : value).append(permutation)); } } private static class JobsInterval { public int jobs; public int interval; public JobsInterval(int j, int i) { jobs = j; interval = i; } public String toString() { return new StringBuilder().append('{').append(jobs).append(", ").append(interval).append('}').toString(); } } } </code></pre>
 

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