combination-sum

Solution.java

@@ -0,0 +1,30 @@
+
+import java.util.ArrayList;
+import java.util.List;
+
+class Solution {
+    public static void main(String []args){
+     int []nums={2,3,6,7};
+     int target=7;
+        System.out.println(combinationSum(nums,target));
+    }
+    public static List<List<Integer>> combinationSum(int[] candidates, int target) {
+        List<List<Integer>>ans=new ArrayList<>();
+        generate(candidates,target,0,ans,new ArrayList<>());
+        return ans;
+    }
+    public static void generate(int []candidates,int target,int i,List<List<Integer>>ans,List<Integer>al){
+        if(target==0){
+            ans.add(new ArrayList<>(al));
+            return;
+        }
+        while(i<candidates.length){
+            if(candidates[i]<=target){
+                al.add(candidates[i]);
+                generate(candidates,target-candidates[i],i,ans,al);
+                al.remove(al.size()-1);
+            }
+            i++;
+        }
+    }
+}