Distributed Median,Alice has an array A, and Bob has an array B. All elements in A and B are distinct. Alice and Bob are interested in finding the median element of their combined arrays.
Floyd-Warshall算法描述
1)適用范圍：
a)APSP(All Pairs Shortest Paths)
b)稠密圖效果最佳
c)邊權(quán)可正可負(fù)
2)算法描述：
a)初始化：dis[u,v]=w[u,v]
b)For k:=1 to n
For i:=1 to n
For j:=1 to n
If dis[i,j]>dis[i,k]+dis[k,j] Then
Dis[I,j]:=dis[I,k]+dis[k,j]
c)算法結(jié)束：dis即為所有點(diǎn)對(duì)的最短路徑矩陣
3)算法小結(jié)：此算法簡(jiǎn)單有效，由于三重循環(huán)結(jié)構(gòu)緊湊，對(duì)于稠密圖，效率要高于執(zhí)行|V|次Dijkstra算法。時(shí)間復(fù)雜度O(n^3)。
考慮下列變形：如(I,j)∈E則dis[I,j]初始為1,else初始為0，這樣的Floyd算法最后的最短路徑矩陣即成為一個(gè)判斷I,j是否有通路的矩陣。更簡(jiǎn)單的，我們可以把dis設(shè)成boolean類型，則每次可以用“dis[I,j]:=dis[I,j]or(dis[I,k]and dis[k,j])”來(lái)代替算法描述中的藍(lán)色部分，可以更直觀地得到I,j的連通情況。
A salient-boundary extraction software package based on the paper: S. Wang, T. Kubota, J. M. Siskind, J. Wang. Salient Closed Boundary Extraction with Ratio Contour, IEEE Transactions on Pattern Analysis and Machine Intelligence, 27(4):546-561, 2005
