Package edu.princeton.cs.algs4
Class GlobalMincut
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- edu.princeton.cs.algs4.GlobalMincut
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public class GlobalMincut extends Object
TheGlobalMincutclass represents a data type for computing a global minimum cut in a graph with non-negative edge weights. A cut is a partition of the vertices into two nonempty subsets. An edge that has one endpoint in each subset of a cut is a crossing edge. The weight of a cut is the sum of the weights of its crossing edges. A global minimum cut whose weight is no larger than the weight of any other cut.This is an implementation of Stoer-Wagner's algorithm. The constructor takes O(V (V + E) log V) time, where V is the number of vertices and E is the number of edges. The weight and isCut methods take Θ(1) time. It uses Θ(V) extra space (not including the graph).
For additional documentation, see
- M. Stoer and F. Wagner (1997). A simple min-cut algorithm. Journal of the ACM , 44(4):585-591.
- Author:
- Marcelo Silva
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Constructor Summary
Constructors Constructor Description GlobalMincut(EdgeWeightedGraph G)Computes a minimum cut in an edge-weighted graph.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description booleancut(int v)Returnstrueif the vertexvis one side of the mincut andfalseotherwise.static voidmain(String[] args)Unit tests theGlobalMincutdata type.doubleweight()Returns the weight of the minimum cut.
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Constructor Detail
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GlobalMincut
public GlobalMincut(EdgeWeightedGraph G)
Computes a minimum cut in an edge-weighted graph.- Parameters:
G- the edge-weighted graph- Throws:
IllegalArgumentException- if the number of vertices ofGis less than2.IllegalArgumentException- if any edge weight is negative
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Method Detail
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weight
public double weight()
Returns the weight of the minimum cut.- Returns:
- the weight of the minimum cut
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cut
public boolean cut(int v)
Returnstrueif the vertexvis one side of the mincut andfalseotherwise. An edge v-w crosses the mincut if and only if v and w have opposite parity.- Parameters:
v- the vertex to check- Returns:
trueif the vertexvis on the first subset of vertices of the minimum cut; orfalseif the vertexvis on the second subset.- Throws:
IllegalArgumentException- unless vertexvis between0 <= v < V
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main
public static void main(String[] args)
Unit tests theGlobalMincutdata type.- Parameters:
args- the command-line arguments
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