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permutations.dart (893B)

      1 //Find and return all possible permutations of a given set of integers
      2 //To do this I used recursion to create a decision tree that splits off each time
      3 //depending on how many integers in the list are unused.
      4 //The time complexity of this code is O(n!)
      5 //Time: 276ms Beats: 50%
      6 //Memory: 142.7MB Beats: 33.33%
      7 
      8 class Solution {
      9   List<List<int>> return_list = [];
     10   List<List<int>> permute(List<int> nums) {
     11       recurse(nums, []);
     12       return return_list;
     13   }
     14   void recurse(List<int> vals , List<int> current){
     15       if(vals.length == 1){
     16           current.add(vals[0]);
     17           return_list.add(current);
     18           return;
     19       }
     20       for(int i = 0 ; i < vals.length ; ++i){
     21           List<int> original = List.from(vals);
     22           List<int> curr = List.from(current);
     23           curr.add(original[i]);
     24           original.removeAt(i);
     25           recurse(original, curr);
     26       }
     27   }
     28 }