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来自「浙江大学计算机学院数据结构课程的教学课件」· HTM 代码 · 共 45 行
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<b><font face="Arial, Helvetica, sans-serif" size="4" color="#000000">⑵<font color="#FF0000"> All pairs shortest paths </font>
Using the above shortestpath algorithm , find the shortest path
between all pairs of vertices , <img src="image/vivj.gif" width="148" height="28" align="middle">
<font color="#FF0000"> complexity</font> = <img src="image/text6-y.gif" width="196" height="26" align="middle">
<font color="#FF0000">G</font> ~ cost adjacency matrix
<img src="image/text6-z.gif" width="66" height="20" align="middle"> ~ the cost of the shortest path from i to j, using only these
intermediate vertices with an index <=k .
<img src="image/text6-a1.gif" width="75" height="19" align="middle"> ~ the cost of the shortest path from i to j
<img src="image/text6-a3.gif" width="70" height="20" align="middle"> = cost [i ] [j ]
<font color="#FF0000">Rules </font>for <img src="image/text6-a4.gif" width="76" height="20"> -----> <img src="image/text6-z.gif" width="66" height="20">
(1) the shortest path from i to j going through no vertices with
index greater than k does not go through the vertex with index
k and so its cost is <img src="image/text6-a4.gif" width="76" height="20" align="middle"> .
(2) the shortest such path does go through vertex k,
path i to j = path i to k + path k to j ( indices <= k-1)
</font></b><img src="image/text6-a1c.gif" width="597" height="27">
<b><font face="Arial, Helvetica, sans-serif" size="4" color="#000000"><img src="image/text6-a3.gif" width="88" height="26" align="middle"></font></b> <b><font face="Arial, Helvetica, sans-serif" size="4" color="#000000">= cost [i ] [j ]</font></b></pre>
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