class Solution { public: int numberOfSubmatrices(vector>& grid) { int n=grid.size(); int m=grid[0].size(); vector> prex(n+1,vector(m+1,0)); vector> prey(n+1,vector(m+1,0)); for(int i=1;i0){res++;} } } return res; } };
二维前缀和 前缀和数组定义时扩宽一层