add cpp version, use three way partition algorithm

Author: zouwx2cs

solution/0075.Sort Colors/Solution2.cpp

@@ -0,0 +1,19 @@
+// 三路partition算法(0ms)
+class Solution {
+public:
+    void sortColors(vector<int>& nums) {
+        vector<int>::iterator next_lower = nums.begin() ;
+        vector<int>::iterator next_cmp = nums.begin() ; 
+        vector<int>::iterator next_bigger = nums.end()-1 ;
+        
+        while (next_cmp <= next_bigger)
+        {
+                if (*next_cmp < 1)
+                    swap(*next_lower++, *next_cmp++) ;
+                else if (*next_cmp > 1)
+                    swap(*next_bigger--, *next_cmp) ;
+                else
+                    ++next_cmp ;
+        }
+    }
+};