LeetCode1005. K 次取反后最大化的数组和

 1 class Solution {
 2 public:
 3     int largestSumAfterKNegations(vector<int>& A, int k) {
 4         int sum = 0;
 5         while(k){
 6             sort(A.begin(),A.end());
 7             A[0] = -A[0];
 8             k--;
 9         }
10         
11         for(int i = 0;i < A.size();i++){
12             sum += A[i];
13         }
14         return sum; 
15     }
16 };

 1 class Solution {
 2 public:
 3     //按绝对值从大到小进行排列
 4     static bool cmp(int a,int b){
 5         return abs(a) > abs(b);
 6     }
 7     int largestSumAfterKNegations(vector<int>& A, int k) {
 8         int sum = 0;
 9         sort(A.begin(),A.end(),cmp);
10         //把负数变正数
11         for(int i = 0;i < A.size();i++){
12             if(A[i] < 0 && k >0){
13                 A[i] = -A[i];
14                 k--;
15             }
16         }
17         //最后反复变值最小的正数
18         while(k--) {
19             A[A.size()-1] *= -1;
20         }
21         for(int i = 0;i < A.size();i++){
22             sum += A[i];
23         }
24         return sum; 
25     }
26 };