Combination Sum 문제 풀이

Author: ymir0804

combination-sum/ymir0804.java

@@ -0,0 +1,31 @@
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+class Solution {
+   public List<List<Integer>> combinationSum(int[] candidates, int target) {
+       List<List<Integer>> result = new ArrayList<>();
+       Arrays.sort(candidates);
+       backtrack(candidates, target, new ArrayList<>(), result, 0);
+       return result;
+    }
+
+
+    public void backtrack(int[] candidates, int remain, List<Integer> current, List<List<Integer>> result, int start) {
+        if (remain < 0) {
+            return;
+        }
+        if (remain == 0) {
+            result.add(new ArrayList<>(current));
+            return;
+        }
+
+        for (int i = start; i < candidates.length; i++) {
+
+            if (candidates[i] > remain) break;
+            current.add(candidates[i]);
+            backtrack(candidates, remain - candidates[i], current, result, i);
+            current.remove(current.size() - 1);
+        }
+    }
+}