作者VeranoDB (StarNighT)
看板Prob_Solve
標題[問題] DAG找最短路徑問題
時間Sun Feb 3 18:30:06 2013
最近友人問我一個演算法的考題
找了很多資料還是不太會想請教大大們
Let G be a direct acyclic graph with vertex set V and arc set E. Suppose that
s is the only vertwx with in-degree zero. Consider following for finding the
shorest path lengths from s to all the other vertices. Here each arc has unit
length.
Algorithm TTT
find a (__) (v1=s,v2,...,vn) of G // What kind of sequence it is
set d[1]=0 and d[i]=n for any i>1;
for i from 1 to n-1 do
for each j such that there is an arc (vi,vj) do
if (__) then (__)
the time complexity is O(__)
問這4個填空
我只有找到是最後一個好像是O(|V|+|E|)
不知道可不可以在這問，如果不行我會刪除
感謝!
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◆ From: 1.168.102.152
※ 編輯: VeranoDB 來自: 1.168.102.152 (02/03 18:31)
1F：→ suhorng:第一個空格應該跟拓樸順序有關 02/03 20:32
2F：→ suhorng:第二, 三個空格就是 relax, 比較短就放鬆 02/03 20:32
3F：推 singlovesong:topological sorted order, d[vi]+arc(vi,vj) <d[vj] 02/03 23:08
4F：→ singlovesong:d[vj] = d[vi] + arc(vi,vj) 02/03 23:08
5F：→ singlovesong:猜的 02/03 23:08
6F：→ VeranoDB:感謝回答 02/07 00:15