Create yeonguchoe.java

Author: YeonguChoe

combination-sum/yeonguchoe.java

@@ -0,0 +1,30 @@
+class Solution {
+    // Time complexity: O(candidate^(target/smallest candidate))
+    // Space complexity: O(target/smallest candidate)
+
+    List<List<Integer>> result = new ArrayList<>();
+
+    public void backtracking(int remainingAmount, List<Integer> combination, int startPoint, int[] candidateList,
+            List<List<Integer>> resultList) {
+        if (remainingAmount == 0) {
+            resultList.add(new ArrayList<>(combination));
+            return;
+        }
+
+        if (remainingAmount < 0) {
+            return;
+        }
+
+        for (int i = startPoint; i < candidateList.length; i++) {
+            combination.add(candidateList[i]);
+            backtracking(remainingAmount - candidateList[i], combination, i, candidateList, resultList);
+            combination.remove(combination.size() - 1);
+        }
+    }
+
+    public List<List<Integer>> combinationSum(int[] candidates, int target) {
+        ArrayList<Integer> initialCombination = new ArrayList<>();
+        backtracking(target, initialCombination, 0, candidates, result);
+        return result;
+    }
+}