adding iterator exercise

leetcode/p283_movezeroes.cpp

@@ -0,0 +1,21 @@
+class Solution {
+public:
+    void moveZeroes(vector<int>& nums) {
+        vector<int>::iterator itr = nums.begin();
+        // use itr2 to represent the "new" vector
+        vector<int>::iterator itr2 = nums.begin();
+        while(itr != nums.end()){
+            // traverse the vector and store all non-zero elements in the "new" vector.
+            if(*itr != 0){
+                *itr2 = *itr;
+                itr2++;
+            }
+            itr++;
+        }
+        // as we skipped zeroes above, we now fill them in.
+        while(itr2!=nums.end()){
+            *itr2 = 0;
+            itr2++;
+        }
+    }
+};