Objective-C?????-????

???-????????????????????????????????????????????????Objective-C?????????????????????

#import <Foundation/Foundation.h>

@interface Edge : NSObject

@property (nonatomic) NSInteger source;@property (nonatomic) NSInteger destination;@property (nonatomic) NSInteger weight;@end>

@interface BellmanFord : NSObject

@property (nonatomic, strong) NSArray *edges;@property (nonatomic) NSInteger sourceNode;@property (nonatomic) NSInteger numberOfNodes;

• (void)initializeDistances;
• (void)relaxEdge:(Edge *)edge;
• (void)bellmanFordAlgorithm;
• (void)printResults;
  @end>

@implementation BellmanFord

• (void)initializeDistances

  {
  self.distance = [NSArray array];
  for (NSInteger i = 0; i < numberOfNodes; i++)
  {
  self.distance[i] = INFINITY;
  if (i == sourceNode)
  {
  self.distance[i] = 0;
  }
  }
  }

• (void)relaxEdge:(Edge *)edge

  {
  NSInteger u = edge.source;
  NSInteger v = edge.destination;
  NSInteger weight = edge.weight;

  if (distance[u] + weight < distance[v])

  {
  distance[v] = distance[u] + weight;
  // ?????????????????
  }
  }

• (void)bellmanFordAlgorithm

  {
  initializeDistances();
  for (NSInteger i = 0; i < numberOfNodes; i++)
  {
  for (Edge *edge in edges)
  {
  relaxEdge(edge);
  }
  }

  // ????????

  // ???????????????
  while (true)
  {
  Boolean updated = false;
  for (Edge *edge in edges)
  {
  if (distance[edge.source] != INFINITY && distance[edge.destination] == INFINITY)
  {
  distance[edge.destination] = distance[edge.source] + edge.weight;
  updated = true;
  }
  }

  if (!updated)

  {
  break;
  }
  }

  printResults();

  }

• (void)printResults

  {
  NSLog(@"?????");
  for (NSInteger i = 0; i < numberOfNodes; i++)
  {
  NSLog(@"?? %d ?????????? %f", i, distance[i]);
  }
  }

  ??????????????`BellmanFord`???????-???????????????

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  • edges?????????
  • sourceNode????
  • numberOfNodes????????
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  BellmanFord *bellman = [[BellmanFord alloc] init]; bellman.sourceNode = 1; bellman.numberOfNodes = 4; bellman.edges = @[[Edge edgeWithSource:1 destination:2 weight:2], [Edge edgeWithSource:1 destination:3 weight:5], [Edge edgeWithSource:2 destination:3 weight:-1]]; [bellman bellmanFordAlgorithm];

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