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Permutations

Given a collection of numbers, return all possible permutations.

For example,
[1,2,3] have the following permutations:
[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].

public static List
   
    
     > permute(int[] num) {		LinkedList ans = new LinkedList<>(); // queue		ans.offer(new LinkedList
     
      ()); // init with empty list		// loop through sizes of lists used for inserting new element in asc		// order		for (int n = 0; n < num.length; n++) {			// loop through all lists of a current size			while (n == ((List
      
       
        >) ans.peek()).size()) {				List
        
          l = (List
         
          ) ans.poll(); // next "base" // list of a // curr size // loop through all position in a "base" list generating new // list for (int i = 0; i <= l.size(); i++) { LinkedList
          
            newL = new LinkedList<>(l.subList(0, i)); newL.add(num[n]); newL.addAll(l.subList(i, l.size())); ans.offer(newL); } } } return ans; } public static void main(String[] arqs) { int[] num = new int[] { 1, 2, 3 }; List
           
            
             > result = permute(num); Iterator ite = result.iterator(); while (ite.hasNext()) { List
             
               list = (List
              
               ) ite.next(); Iterator ite_2 = list.iterator(); System.out.print("{"); while (ite_2.hasNext()) { int x = (Integer) ite_2.next(); System.out.print(x); } System.out.print("}\n"); } }
              
             
            
           
          
         
        
       
      
     
    
   

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