combination sum solved

Author: sora0319

combination-sum/sora0319.java

@@ -0,0 +1,26 @@
+import java.util.*;
+class Solution {
+    public List<List<Integer>> combinationSum(int[] candidates, int target) {
+        List<List<Integer>> output = new ArrayList<>();
+        List<Integer> sum = new ArrayList<>();
+        checkTarget(candidates, target, 0, output, sum);
+        return output;
+    }
+
+    private void checkTarget(int[] candidates, int target, int start, List<List<Integer>> output, List<Integer> sum) {
+        if (target == 0) {
+            output.add(new ArrayList<>(sum));
+            return;
+        }
+
+        for (int i = start; i < candidates.length; i++) {
+            int current = candidates[i];
+            if (current > target) continue;
+
+            sum.add(current);
+            checkTarget(candidates, target - current, i, output, sum);
+            sum.remove(sum.size() - 1);
+        }
+    }
+}
+