All Pairs Shortest Path Floyd Warshall Algorithm

#TC=O(v**3)
class Solution:
    def shortest_distance(self, mat):
        v=len(mat)
        for i in range(v):
            for j in range(v):
                if mat[i][j]==-1:
                    mat[i][j]=float('inf')
        for k in range(v):
            for i in range(v):
                for j in range(v):
                    mat[i][j]=min(mat[i][k]+mat[k][j],mat[i][j])
        for i in range(v):
            for j in range(v):
                if mat[i][j]==float('inf'):
                    mat[i][j]=-1
        return mat