拓扑排序通常用于确定一个流程，结果并不一定是唯一的。具体的套路是：

1. 找入度为0的点入栈，如果没有入度为0的点，说明必然有环路。

• 依此处栈，对于每个出栈的元素，检查它的所有边集，对边集上的每个点的入度-1。
• 若某点入度变成了1，说明这个点变成了孤家寡人，应该入栈
• 第二步，直到全部元素出栈。
• 若出栈元素小于总元素数，说明必有环路。

//拓扑排序
//顶点
function Vertex(name) {
  this.name =name;
  this.in = 0;
}
Vertex.prototype.setFirstedge = function(edgeNode) {
  this.firstEdge = edgeNode;
  edgeNode.adjVex.in++;
};
Vertex.prototype.setNext = function(edgeNode){
  var temp = this.firstEdge;
  if(!temp){
    this.firstEdge = edgeNode;
    edgeNode.adjVex.in++;
    return;
  }else{
    while(temp){
      var temp1 = temp.next;
      if(!temp1){
        temp.next = edgeNode;
        edgeNode.adjVex.in++;
        break;
      }else{
        temp = temp.next;
      }
    }
  }
}
//边
function EdgeNode(){
  this.adjVex = arguments[0];
  this.weight = arguments[1] ? arguments[1] : undefined;
}
//图
function Graph(vertexs,numEdges){
  this.vertexs = vertexs;
  this.numVertexs = this.vertexs.length;
  this.numEdges =numEdges;
}
//需要引入栈进行计算
function Node(data) {
    this.data = data;
}
function Stack(maxSize){
    this.maxSize = maxSize;
    this.top = -1;
    this.data = new Array(maxSize);
}
Stack.prototype.push = function(node){
    if(this.top == this.maxSize-1){
        return 1;
    }
    this.top++;
    this.data[this.top] = node;
    return 0;
}
Stack.prototype.pop = function(){
    if(this.top==-1){
        return 1;
    }
    var r = this.data[this.top];
    this.data[this.top] = undefined;
    this.top--;
    return r;
}
Stack.prototype.ergodic = function(){
  var s = '';
  for (var i = 0; i < this.data.length; i++) {
    if(this.data[i]!=null){
        s += this.data[i]+',';
    }
  }
  if(s.length){
    s = s.substring(0,s.length-1);
  }
  return s;
}
Stack.prototype.length = function(){
  return this.top+1;
}
Graph.prototype.topologicalSort = function() {
  var top = 0,count = 0;
  var gettop,k;
  var result ='';//结果
  var stack = new Stack(this.numVertexs)
  for (var i = 0; i < this.numVertexs; i++) {
    if(this.vertexs[i].in==0){
      stack.push(i);
    }
  }
  console.info('初始化完毕（将入度为0的顶点入栈），当前堆栈'+stack.ergodic());
  while(stack.length()){
    console.info('当前栈：'+stack.ergodic());
    gettop = stack.pop();
    result += this.vertexs[gettop].name +' ';
    count++;
    console.info('剥离点'+this.vertexs[gettop].name);
    for (var e = this.vertexs[gettop].firstEdge; e; e=e.next) {
      k = this.vertexs.indexOf(e.adjVex);
      if(!(--this.vertexs[k].in)){
        console.info('发现'+this.vertexs[k].name+'入度仅仅为1，必须入栈剥离');
        stack.push(k);
      }
    }
  }
  if(count<this.numVertexs){
    console.info('发生错误，有环路存在');
    return false;
  }
  console.info(result);
  return true;
};
var v0 = new Vertex('v0');
var v1 = new Vertex('v1');
var v2 = new Vertex('v2');
var v3 = new Vertex('v3');
var v4 = new Vertex('v4');
var v5 = new Vertex('v5');
var v6 = new Vertex('v6');
var v7 = new Vertex('v7');
var v8 = new Vertex('v8');
var v9 = new Vertex('v9');
var v10 = new Vertex('v10');
var v11 = new Vertex('v11');
var v12 = new Vertex('v12');
var v13 = new Vertex('v13');
v0.setNext(new EdgeNode(v11));
v0.setNext(new EdgeNode(v5));
v0.setNext(new EdgeNode(v4));
v1.setNext(new EdgeNode(v8));
v1.setNext(new EdgeNode(v4));
v1.setNext(new EdgeNode(v2));
v2.setNext(new EdgeNode(v9));
v2.setNext(new EdgeNode(v6));
v2.setNext(new EdgeNode(v5));
v3.setNext(new EdgeNode(v13));
v3.setNext(new EdgeNode(v2));
v4.setNext(new EdgeNode(v7));
v5.setNext(new EdgeNode(v12));
v5.setNext(new EdgeNode(v8));
v6.setNext(new EdgeNode(v5));
v8.setNext(new EdgeNode(v7));
v9.setNext(new EdgeNode(v11));
v9.setNext(new EdgeNode(v10));
v10.setNext(new EdgeNode(v13));
v12.setNext(new EdgeNode(v9));
var g = new Graph([v0,v1,v2,v3,v4,v5,v6,v7,v8,v9,v10,v11,v12,v13],20);
g.topologicalSort();

OUTPUT

初始化完毕（将入度为0的顶点入栈），当前堆栈0,1,3
当前栈：0,1,3
剥离点v3
当前栈：0,1
剥离点v1
发现v2入度仅仅为1，必须入栈剥离
当前栈：0,2
剥离点v2
发现v6入度仅仅为1，必须入栈剥离
当前栈：0,6
剥离点v6
当前栈：0
剥离点v0
发现v5入度仅仅为1，必须入栈剥离
发现v4入度仅仅为1，必须入栈剥离
当前栈：5,4
剥离点v4
当前栈：5
剥离点v5
发现v12入度仅仅为1，必须入栈剥离
发现v8入度仅仅为1，必须入栈剥离
当前栈：12,8
剥离点v8
发现v7入度仅仅为1，必须入栈剥离
当前栈：12,7
剥离点v7
当前栈：12
剥离点v12
发现v9入度仅仅为1，必须入栈剥离
当前栈：9
剥离点v9
发现v11入度仅仅为1，必须入栈剥离
发现v10入度仅仅为1，必须入栈剥离
当前栈：11,10
剥离点v10
发现v13入度仅仅为1，必须入栈剥离
当前栈：11,13
剥离点v13
当前栈：11
剥离点v11
v3 v1 v2 v6 v0 v4 v5 v8 v7 v12 v9 v10 v13 v11
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