leetcode:螺旋矩阵ii

class :
    def generateMatrix(self, n: int) -> List[List[int]]:
        if n == 0: return []
        res=[]
        for i in range(n):
            tmp=[]
            for j in range(n):
                tmp.append(0)
            res.append(tmp)
            
        u = 0
        d = n-1
        l = 0
        r = n-1  
        num=1
        
        while(True):
            for i in range(l,r+1):
                res[u][i]=num
                num+=1
            u+=1
            
            if(u > d) :
                break
                
            for i in range(u,d+1):
                res[i][d]=num
                num+=1
            r-=1
            
            if(l > r) :
                break
            
            for i in range(r,l-1,-1):
                res[d][i]=num
                num+=1
            d-=1
           
            if(u > d) :
                break
                
            for i in range(d,u-1,-1):
                res[i][l]=num
                num+=1
            l+=1
            
            if(l > r) :
                break
            
        return res