leetcode

commit f8681a944ce6dfa01de18bebb9163457144c2938
parent 9d870d3de396c3e2057710f65f6578b041e103ee
Author: AndrewLockVI <andrewlaack1@gmail.com>
Date:   Fri, 26 May 2023 16:17:05 -0500

Completed combinations problem using recursion and dart

Diffstat:
A
combinations/combinations.dart
 | 
36
++++++++++++++++++++++++++++++++++++

1 file changed, 36 insertions(+), 0 deletions(-)
diff --git a/combinations/combinations.dart b/combinations/combinations.dart
@@ -0,0 +1,36 @@
+//Given an input where n is the number of values and 
+//k is the length of each combination return all possible combinations.
+//My solution iterates through the list and returns
+//each possible combination each time it iterates the first
+//index of the list moves one to the right as to not return both
+//1,2 and 2,1 which would happen if you returned all permutations
+//of the second index.
+//Time: 279ms Beats: 83.33%
+//Memory: 155.6MB Beats: 30.56%
+
+class Solution {
+  List<List<int>> combine(int n, int k) {
+      List<int> values = [];
+      for(int i = 1 ; i < n + 1; ++i){
+          values.add(i);
+      }
+      return allCombinations(k, values, []);
+  }
+  List<List<int>> allCombinations(int length , List<int> options, List<int> current){
+      if(length == current.length){
+          return [current];
+      }
+      List<List<int>> return_list = [];
+      for(int i = 0; i <  options.length ; ++i){
+          List<int> new_curr = List.from(current);
+          List<int> opts = List.from(options);
+          opts = opts.sublist(i + 1);
+          new_curr.add(options[i]);
+          List<List<int>> ret = allCombinations(length , opts, new_curr);
+          for(int i = 0 ; i < ret.length ; ++i){
+              return_list.add(ret[i]);
+          }
+      }
+      return return_list;
+  }
+}