Update 216_Combination_Sum_III.java

Author: Sean Prashad

Backtracking/216_Combination_Sum_III.java

@@ -1,20 +1,20 @@
 class Solution {
     public List<List<Integer>> combinationSum3(int k, int n) {
         List<List<Integer>> result = new ArrayList<>();
-        dfs(k, n, 1, new ArrayList<>(), result);
+        helper(n, k, 1, new ArrayList<>(), result);
         return result;
     }
 
-    private void dfs(int k, int n, int idx, List<Integer> tempResult, List<List<Integer>> result) {
-        if (tempResult.size() == k && n == 0) {
-            result.add(new ArrayList<>(tempResult));
+    private void helper(int n, int numsAllowed, int start, List<Integer> temp, List<List<Integer>> result) {
+        if (numsAllowed == 0 && n == 0) {
+            result.add(new ArrayList<>(temp));
             return;
         }
 
-        for (int i = idx; i <= 9; i++) {
-            tempResult.add(i);
-            dfs(k, n - i, i + 1, tempResult, result);
-            tempResult.remove(tempResult.size() - 1);
+        for (int i = start; i <= 9; i++) {
+            temp.add(i);
+            helper(n - i, numsAllowed - 1, i + 1, temp, result);
+            temp.remove(temp.size() - 1);
         }
     }
 }