剑指21: 调整奇数到偶数前

 1 class Solution {
 2 public:
 3     vector<int> exchange(vector<int>& nums) {
 4         if(nums.empty()) return nums;
 5         return myexchange(nums,isEven);
 6     }
 7 
 8     vector<int> myexchange(vector<int>& nums, bool(*func)(int)){
 9         auto head=nums.begin(), tail=nums.end()-1;
10         while(head<tail){
11             while(head<tail && !func(*head))
12                 head++;
13 
14             while(head<tail && func(*tail))
15                 tail--;
16 
17             if(head<tail){
18                 int temp=*head;
19                 *head=*tail;
20                 *tail=temp;
21             }
22         }
23         return nums;
24     }
25 
26     static bool isEven(int n){
27         return (n&1)==0?true:false;
28     }
29 };