39. Combination Sum (java)

Author: bluesword12350

solution/0039.Combination Sum/Solution.java

@@ -0,0 +1,21 @@
+class Solution {
+    public List<List<Integer>> combinationSum(int[] candidates, int target) {
+        List<List<Integer>> result = new ArrayList<>();
+        Arrays.sort(candidates);
+        combinationSum(candidates,target,candidates.length-1, new ArrayList<>(),result);
+        return result;
+    }
+
+    private void combinationSum(int[] candidates, int target,int length, List<Integer> integers,
+                                List<List<Integer>> result) {
+        List<Integer> list;
+        for (int i = length; i >= 0; i--) {
+            int nc = candidates[i];
+            if (nc>target) continue;
+            list = new ArrayList<>(integers);
+            list.add(nc);
+            if (nc==target) result.add(list);
+            else combinationSum(candidates, target - nc, i, list,result);
+        }
+    }
+}