Merge pull request gzc426#774 from MMzhe/patch-54

Create sourcema.md

Author: gzc426

2019.01.20-leetcode216/sourcema.md

@@ -0,0 +1,25 @@
+# leetcode 216
+    class Solution {
+    public List<List<Integer>> combinationSum3(int k, int n) {
+         List<List<Integer>> res = new ArrayList<>();
+        if (k <= 0 || n <= 0) {
+            return res;
+        }
+        find(res, new ArrayList<Integer>(), k, n,1);
+        return res;
+    }
+    private static void find(List<List<Integer>> res, ArrayList<Integer> list, int k, int n,int num) {
+        if (list.size() == k && n == 0) {
+            res.add(new ArrayList<Integer>(list));
+            return;
+        }
+        if (list.size() >= k) {
+            return;
+        }
+        for (int i = num; i <=9&&i<=n ; i++) {
+            list.add(i);
+            find(res,list,k,n-i,i+1);
+            list.remove(list.size() - 1);
+        }
+    }
+}