Added solution for iterator for combination

Author: avidLearnerInProgress

iterator_for_combination.cpp

@@ -0,0 +1,30 @@
+class CombinationIterator {
+    string s;
+    queue<string> q;
+    
+    void getCombination(int start, int length, string txt){
+        if(length == 0){
+            q.push(txt);
+            return;
+        }
+        
+        for(int i = start; i <= s.length() - length; ++i)
+            getCombination(i+1, length-1, txt + s[i]);
+    }
+public:
+    CombinationIterator(string characters, int combinationLength) {
+        s = characters;
+        string txt = "";
+        getCombination(0, combinationLength, txt);
+    }
+    
+    string next() {
+        string str = q.front();
+        q.pop();
+        return str;
+    }
+    
+    bool hasNext() {
+        return !q.empty();
+    }
+};