add chap 22

Chapter22_ElementaryGraphAlgorithms.md

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+第22章 图基本算法
+=
+##22.1 图的表示  
+#####22.1-1 Given an adjacency-list representation of a directed graph, how long does it take to compute the out-degree of every vertex? How long does it take to compute the in-degrees?  
+G=(V,E)。  
+out-degree:O(V+E)  
+in-degree:O(V+E)  
+
+#####22.1-2 Give an adjacency-list representation for a complete binary tree on 7 vertices. Give an equivalent adjacency-matrix representation. Assume that vertices are numbered from 1 to 7 as in a binary heap.  
+ | 1 | 2 | 3 | 4 | 5 | 6 | 7
+:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:
+1 | 0 | 1 | 1 | 0 | 0 | 0 | 0
+2 | 1 | 0 | 0 | 1 | 1 | 0 | 0
+3 | 1 | 0 | 0 | 0 | 0 | 1 | 1
+4 | 0 | 1 | 0 | 0 | 0 | 0 | 0 
+5 | 0 | 1 | 0 | 0 | 0 | 0 | 0
+6 | 0 | 0 | 1 | 0 | 0 | 0 | 0
+7 | 0 | 0 | 1 | 0 | 0 | 0 | 0
+
+### 22.1-3