Add combination sum solution - s0ooo0k

Author: s0ooo0k

combination-sum/s0ooo0k.java

@@ -0,0 +1,23 @@
+class Solution {
+    List<List<Integer>> result = new ArrayList<>();
+    int[] candidates;
+
+    public List<List<Integer>> combinationSum(int[] candidates, int target) {
+        this.candidates=candidates;
+        backtrack(new ArrayList<>(), target, 0);
+        return result;
+    }
+    void backtrack(List<Integer> comb, int remain, int start) {
+        if(remain==0) {
+            result.add(new ArrayList<>(comb));
+            return;
+        }
+        if(remain<0) return;
+        for(int i=start; i<candidates.length; i++) {
+            comb.add(candidates[i]);
+            backtrack(comb, remain-candidates[i], i);
+            comb.remove(comb.size() - 1);
+        }
+    }
+}
+