Leetcode-1005 Maximize Sum Of Array After K Negations(K 次取反后最大化的数组和)

#define pb push_back
#define _for(i,a,b) for(int i = (a);i < (b);i ++)
const int maxn = 50003;

class Solution
{
    public:
        int largestSumAfterKNegations(vector<int>& A, int K)
        {
            int hash[202] {0};
            int fnum = 0;
            _for(i,0,A.size())
            {
                if(A[i]<0)
                    fnum ++;
                hash[A[i]+100] ++;
            } 
            if(fnum<=K)
            {
                
                _for(i,0,100)
                {
                    hash[200-i] += hash[i];
                    hash[i] = 0; 
                }
                K -= fnum;
                
                if(K&0x1)
                {
                    _for(i,100,201)
                    {
                        if(hash[i])
                        {
                            hash[200-i]++;
                            hash[i] --;
                            break;
                        }
                    }
                }
            }
            else
            {
                int index = 0;
                while(K --)
                {
                    while(hash[index]==0)
                        index ++;
                    hash[index] --;
                    hash[200-index] ++; 
                }
            }

            int rnt = 0;
            _for(i,0,201)
            {
                rnt += hash[i] * (i-100);
            }
            return rnt;
        }
};

分类讨论，随便乱搞过了