combination-sum solution

Author: ohgyulim

combination-sum/ohgyulim.java

@@ -0,0 +1,25 @@
+import java.util.*;
+
+class Solution {
+    List<List<Integer>> answer = new ArrayList<>();
+    public List<List<Integer>> combinationSum(int[] candidates, int target) {
+        Arrays.sort(candidates);
+        recur(new ArrayList<Integer>(), candidates, target, 0, 0);
+        return answer;
+    }
+
+    public void recur(List<Integer> result, int[] candidates, int target, int sum, int index) {
+        if (sum == target) {
+            List<Integer> deepCopyRes = new ArrayList<>(result);
+            answer.add(deepCopyRes);
+            return;
+        }
+        for (int i = index; i < candidates.length; i++) {
+            if (sum + candidates[i] <= target) {
+                result.add(candidates[i]);
+                recur(result, candidates, target, sum + candidates[i], i);
+                result.remove(Integer.valueOf(candidates[i]));
+            }
+        }
+    }
+}