Question

我正在用JavaScript构建图形，但遇到了这个问题。

输出不是我想要的。

我对图的了解是每个节点之间都有边和 adjacentList的目标是显示边缘并与节点建立连接。

如果我的代码不完整，请给我提示以完成它，或者只是修复我的代码并满足要求。

输出应为：

Answer:
0-->1 2
1-->3 2 0
2-->4 1 0
3-->1 4
4-->3 2 5
5-->4 6
6-->5

这是我的JS：

 class Graph { 
    constructor() { 
    this.numberOfNodes = 0;
    this.adjacentList = {
    }; 
  } 
  addVertex(node)  { 
    this.adjacentList[node]=[];
    this.numberOfNodes++;
   } 
   addEdge(node1, node2) { 
    this.adjacentList[node1]=[];
    this.adjacentList[node1].push(node2);
   } 
  showConnections() { 
    const allNodes = Object.keys(this.adjacentList); 
    for (let node of allNodes) { 
       let nodeConnections = this.adjacentList[node]; 
       let connections = ""; 
       let vertex;
    for (vertex of nodeConnections) {
        connections += vertex + " ";
      } 
       console.log(node + "-->" + connections); 
      } 
     } 
    } 

    const myGraph = new Graph();
    myGraph.addVertex('0');
    myGraph.addVertex('1');
    myGraph.addVertex('2');
    myGraph.addVertex('3');
    myGraph.addVertex('4');
    myGraph.addVertex('5');
    myGraph.addVertex('6');
    myGraph.addEdge('3', '1'); 
    myGraph.addEdge('3', '4'); 
    myGraph.addEdge('4', '2'); 
    myGraph.addEdge('4', '5'); 
    myGraph.addEdge('1', '2'); 
    myGraph.addEdge('1', '0'); 
    myGraph.addEdge('0', '2'); 
    myGraph.addEdge('6', '5');

    myGraph.showConnections();

Answer 1

对象properties使用分号'而不是等于=来定义。另外，各个属性使用逗号,而不是分号;

分隔

您的摘要：

const newNode={
      this.numberOfNodes = 0;
      this.adjacentList = {
     };

实际上应该是这样的：

const newNode={
      numberOfNodes : 0,
      adjacentList : {
     };

Answer 2

我想出了Map和Set来解决问题。你可以看看。

function Graph() {
  let nodes = new Map()
  
  this.addVertex = node => {
    if(!nodes.has(node)) nodes.set(node, new Set())
  }
  
  this.addEdge = (node, egde) => {
    if(nodes.has(node) && nodes.has(egde)) {
      nodes.get(node).add(egde)
      nodes.get(egde).add(node)
    }
  }
  
  this.showConnections = () => {
    nodes.forEach((node, index) => console.log(`${index} -> ${[...node]}`) )
  }
}

const myGraph  = new Graph()
    myGraph.addVertex('0');
    myGraph.addVertex('1');
    myGraph.addVertex('2');
    myGraph.addVertex('3');
    myGraph.addVertex('4');
    myGraph.addVertex('5');
    myGraph.addVertex('6');
    myGraph.addEdge('3', '1'); 
    myGraph.addEdge('3', '4'); 
    myGraph.addEdge('4', '2'); 
    myGraph.addEdge('4', '5'); 
    myGraph.addEdge('1', '2'); 
    myGraph.addEdge('1', '0'); 
    myGraph.addEdge('0', '2'); 
    myGraph.addEdge('6', '5');

myGraph.showConnections();

Answer 3

addVertex(node)  { 
  this.adjacentList[node]=[]; <---| 
  this.numberOfNodes++;           |
 }                                |  <-- Do the same task
 addEdge(node1, node2) {          |  
  this.adjacentList[node1]=[];----|
  this.adjacentList[node1].push(node2);
}

然后，您应该从this.adjacentList[node1]=[]函数中删除addEdge。并且因为您的图形从双方获取数据：

[{'1': '3'}, {'3': '2'}] =>  3-->1,2

然后您应该以两种方式推送节点

addEdge(node1, node2) {
  this.adjacentList[node1].push(node2);
  this.adjacentList[node2].push(node1);
}

代码应为：

class Graph { 
    constructor() { 
    this.numberOfNodes = 0;
    this.adjacentList = {
    }; 
  } 
  addVertex(node)  { 
    this.adjacentList[node]=[];
    this.numberOfNodes++;
   } 
   addEdge(node1, node2) { 
    // this.adjacentList[node1]=[]; <------------ Remove this line
     this.adjacentList[node1].push(node2);
     this.adjacentList[node2].push(node1); // <-- Add this line
   }
  
  showConnections() { 
    const allNodes = Object.keys(this.adjacentList); 
    for (let node of allNodes) { 
       let nodeConnections = this.adjacentList[node]; 
       let connections = ""; 
       let vertex;
    for (vertex of nodeConnections) {
        connections += vertex + " ";
      } 
       console.log(node + "-->" + connections); 
      } 
     } 
    } 

    const myGraph = new Graph();
    myGraph.addVertex('0');
    myGraph.addVertex('1');
    myGraph.addVertex('2');
    myGraph.addVertex('3');
    myGraph.addVertex('4');
    myGraph.addVertex('5');
    myGraph.addVertex('6');
    myGraph.addEdge('3', '1'); 
    myGraph.addEdge('3', '4'); 
    myGraph.addEdge('4', '2'); 
    myGraph.addEdge('4', '5'); 
    myGraph.addEdge('1', '2'); 
    myGraph.addEdge('1', '0'); 
    myGraph.addEdge('0', '2'); 
    myGraph.addEdge('6', '5');

    myGraph.showConnections();

此外，您应该处理错误并查看showConnection进行优化。

如何在javascript中建立图形？

3 个答案: