Improve language
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@ -22,8 +22,7 @@ and study different ways to represent graphs in algorithms.
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\index{edge}
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A \key{graph} consists of \key{nodes}
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and \key{edges} between them.
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In this book,
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and \key{edges}. In this book,
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the variable $n$ denotes the number of nodes
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in a graph, and the variable $m$ denotes
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the number of edges.
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@ -57,7 +56,7 @@ through edges of the graph.
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The \key{length} of a path is the number of
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edges in it.
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For example, the above graph contains
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the path $1 \rightarrow 3 \rightarrow 4 \rightarrow 5$
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a path $1 \rightarrow 3 \rightarrow 4 \rightarrow 5$
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from node 1 to node 5:
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\begin{center}
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@ -87,7 +86,7 @@ from node 1 to node 5:
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A path is a \key{cycle} if the first and last
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node is the same.
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For example, the above graph contains
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the cycle $1 \rightarrow 3 \rightarrow 4 \rightarrow 1$.
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a cycle $1 \rightarrow 3 \rightarrow 4 \rightarrow 1$.
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A path is \key{simple} if each node appears
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at most once in the path.
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@ -106,7 +105,7 @@ at most once in the path.
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\index{connected graph}
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A graph is \key{connected} if there is path
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A graph is \key{connected} if there is a path
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between any two nodes.
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For example, the following graph is connected:
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\begin{center}
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@ -175,7 +174,7 @@ $\{8\}$.
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A \key{tree} is a connected graph
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that consists of $n$ nodes and $n-1$ edges.
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There is a unique path
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between any two nodes in a tree.
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between any two nodes of a tree.
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For example, the following graph is a tree:
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\begin{center}
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@ -220,7 +219,7 @@ For example, the following graph is directed:
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\end{center}
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The above graph contains
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the path $3 \rightarrow 1 \rightarrow 2 \rightarrow 5$
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a path $3 \rightarrow 1 \rightarrow 2 \rightarrow 5$
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from node $3$ to node $5$,
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but there is no path from node $5$ to node $3$.
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@ -230,7 +229,7 @@ but there is no path from node $5$ to node $3$.
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In a \key{weighted} graph, each edge is assigned
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a \key{weight}.
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Often the weights are interpreted as edge lengths.
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The weights are often interpreted as edge lengths.
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For example, the following graph is weighted:
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\begin{center}
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\begin{tikzpicture}[scale=0.9]
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@ -249,10 +248,10 @@ For example, the following graph is weighted:
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\end{center}
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The length of a path in a weighted graph
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is the sum of edge weights on the path.
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is the sum of the edge weights on the path.
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For example, in the above graph,
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the length of the path
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$1 \rightarrow 2 \rightarrow 5$ is $12$
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$1 \rightarrow 2 \rightarrow 5$ is $12$,
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and the length of the path
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$1 \rightarrow 3 \rightarrow 4 \rightarrow 5$ is $11$.
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The latter path is the \key{shortest} path from node $1$ to node $5$.
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@ -313,7 +312,7 @@ that end at the node,
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and the \key{outdegree} of a node
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is the number of edges that start at the node.
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For example, in the following graph,
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the indegree of node 2 is 2
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the indegree of node 2 is 2,
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and the outdegree of node 2 is 1.
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\begin{center}
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@ -548,7 +547,7 @@ adj[3].push_back({4,5});
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adj[4].push_back({1,2});
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\end{lstlisting}
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The benefit in using adjacency lists is that
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The benefit of using adjacency lists is that
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we can efficiently find the nodes to which
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we can move from a given node through an edge.
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For example, the following loop goes through all nodes
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@ -677,7 +676,7 @@ corresponds to the following matrix:
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\end{center}
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\end{samepage}
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The drawback in the adjacency matrix representation
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The drawback of the adjacency matrix representation
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is that there are $n^2$ elements in the matrix
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and usually most of them are zero.
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For this reason, the representation cannot be used
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@ -753,7 +752,7 @@ For example, the graph
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\begin{samepage}
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can be represented as follows\footnote{In some older compilers, the function
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\texttt{make\_tuple} must be used instead of the braces (for example,
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\texttt{make\_tuple(1,2,5)} instead of \texttt{\{1,2,5\}}.}:
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\texttt{make\_tuple(1,2,5)} instead of \texttt{\{1,2,5\}}).}:
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\begin{lstlisting}
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edges.push_back({1,2,5});
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edges.push_back({2,3,7});
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