分类贪心
lc1975
按负数个数 分类贪心
class Solution {
public:
long long maxMatrixSum(vector<vector<int>>& matrix) {
long long total = 0;
int neg_cnt = 0;
int mn = INT_MAX;
for (auto& row : matrix) {
for (int x : row) {
if (x < 0) {
neg_cnt++;
x = -x;
}
mn = min(mn, x);
total += x;
}
}
if (neg_cnt % 2)
total -= mn * 2; //负数个数分类
return total;
}
};