Create combinations.cpp

Author: avidLearnerInProgress

Diff for: combinations.cpp

@@ -0,0 +1,22 @@
+class Solution {
+public:
+    vector<vector<int>> combine(int n, int k) {
+        vector<vector<int>> output;
+        vector<int> combination;
+        combine(output, combination, n, k, 1);
+        return output;
+    }
+
+private:
+    void combine(vector<vector<int>>& output, vector<int> combination, int n, int k, int i) {
+        if (combination.size() == k) {
+            output.push_back(combination);
+            return;
+        }
+        for (int j = i; j <= n; j++) {
+            combination.push_back(j);
+            combine(output, combination, n, k, j + 1);
+            combination.pop_back();
+        }
+    }
+};