75. 颜色分类

 1 class Solution 
 2 {
 3 public:
 4     void sortColors(vector<int>& nums) 
 5     {
 6         int n = nums.size();
 7         int begin = -1;
 8         int end = n;
 9         int i = 0;
10         while(i < end)
11         {
12             if(nums[i] == 0) swap(nums[++begin],nums[i++]);
13             else if(nums[i] == 1) i++;
14             else swap(nums[--end],nums[i]);
15         }
16     }
17 };