自底向上计算 The heart of the algorithm is the following procedure,which,given matrices L(m-1and W.returns the matrix L(m).That is,it extends the shortest paths com- puted so far by one more edge. EXTEND-SHORTEST-PATHS(L.W) 1 n =L.rows 2 let L'=()be a new n x n matrix 间题4： 3 for i Iton 4 forj 1to n 567 号=∞ one more for k Ito n 号=min(吗，lk+0对) edge”体现在 8 return L' 哪里？自底向上计算 O(n3 )