Magic Squares In Grid（C++矩阵中的幻方）

解题思路：

（1）将不满足条件的列出来，剩下的就是正确的

class Solution {
public:
    int numMagicSquaresInside(vector<vector<int>>& grid) {
    	int count = 0;
    	if (grid.size()<3) return count;
        for (int i=0;i<grid.size()-2;i++) {
        	for (int j=0;j<grid[i].size()-2;j++) {
        		if (Judge(grid[i][j],grid[i][j+1],grid[i][j+2],grid[i+1][j],grid[i+1][j+1],
							grid[i+1][j+2],grid[i+2][j],grid[i+2][j+1],grid[i+2][j+2])) {
					count++;			
				}	
			}
		}
        return count;
    }
    
    bool Judge(int &a,int &b,int &c,int &d,int &e,
    			int &f,int &g,int &h,int &i) {
    	if (e!=5) return false;
		if (a+b+c!=15) return false;
		if (d+e+f!=15) return false;
		if (g+h+i!=15) return false;
		if (a+d+g!=15) return false;
		if (b+e+h!=15) return false;
		if (c+f+i!=15) return false;
		if (a+e+i!=15) return false;
		if (c+e+g!=15) return false;
		set<int> se = {a,b,c,d,e,f,g,h,i};
		if (se.size()!=9 || se.find(0)!=se.end()) return false;
		else return true;
	}
};