树的搜索

树的深度优先搜索

function Node(value) {
  this.value = value;
  this.children = [];
}

var a = new Node("a");
var b = new Node("b");
var c = new Node("c");
var d = new Node("d");
var e = new Node("e");
var f = new Node("f");

a.children.push(c);
a.children.push(b);
a.children.push(f);
b.children.push(d);
b.children.push(e);

// 树的深度优先遍历
function deepLink(root) {
  if (root == null) return;
  console.log(root.value);
  for (var i = 0; i < root.children.length; i++) {
    deepLink(root.children[i]);
  }
}
deepLink(a);

// 树的深度优先搜索
function deepSearch(root, target) {
  if (root == null) return false;
  if (root.value == target) return true;
  var result = false;
  for (var i = 0; i < root.children.length; i++) {
    result |= deepSearch(root.children[i], target);
  }
  return result;
}
console.log(deepSearch(a, "c"));

树的广度优先搜索

function Node(value) {
  this.value = value;
  this.children = [];
}

var a = new Node("a");
var b = new Node("b");
var c = new Node("c");
var d = new Node("d");
var e = new Node("e");
var f = new Node("f");

a.children.push(c);
a.children.push(b);
a.children.push(f);
b.children.push(d);
b.children.push(e);

// 树的广度优先搜索
function bfs(roots, target) {
  if (roots == null || roots.length == 0) return false;
  var childs = [];
  for (var i = 0; i < roots.length; i++) {
    if (roots[i].value == target) return true;
    else {
      childs = childs.concat(roots[i].children);
    }
  }
  return bfs(childs, target);
}
console.log(bfs([a], "m"));

图的搜索

图的深度优先搜索

图的深度优先搜索相比于树来说，就是需要多加判断哪些点是没有走过的

function Node(value) {
  this.value = value;
  this.neighbor = [];
}

var a = new Node("a");
var b = new Node("b");
var c = new Node("c");
var d = new Node("d");
var e = new Node("e");

a.neighbor.push(b);
a.neighbor.push(c);
b.neighbor.push(d);
b.neighbor.push(a);
b.neighbor.push(c);
c.neighbor.push(d);
c.neighbor.push(a);
c.neighbor.push(b);
d.neighbor.push(c);
d.neighbor.push(b);
d.neighbor.push(e);
e.neighbor.push(d);

// 图的深度优先搜索
function deepSearch(node, target, path) {
  // 以node为起点
  if (node == null) return false;
  if (path.indexOf(node) > -1) return false; //找过了
  if (node.value == target) return true;
  path.push(node); //已经查看过的
  var result = false;
  for (var i = 0; i < node.neighbor.length; i++) {
    result |= deepSearch(node.neighbor[i], target, path);
  }
  return result ? true : false;
}

console.log(deepSearch(b, "c", []));

图的广度优先搜索

function Node(value) {
  this.value = value;
  this.neighbor = [];
}

var a = new Node("a");
var b = new Node("b");
var c = new Node("c");
var d = new Node("d");
var e = new Node("e");

a.neighbor.push(b);
a.neighbor.push(c);
b.neighbor.push(d);
b.neighbor.push(a);
b.neighbor.push(c);
c.neighbor.push(d);
c.neighbor.push(a);
c.neighbor.push(b);
d.neighbor.push(c);
d.neighbor.push(b);
d.neighbor.push(e);
e.neighbor.push(d);

// 图的广度优先搜索
function bfs(nodes, target, path) {
  if (nodes.length == 0 || nodes == null) return false;
  var nextNode = [];
  for (var i = 0; i < nodes.length; i++) {
    if (path.indexOf(nodes[i]) > -1) continue; //存在就进行下一次
    path.push(nodes[i]);
    if (nodes[i].value == target) return true;
    else nextNode = nextNode.concat(nodes[i].neighbor);
  }
  return bfs(nextNode, target, path);
}

console.log(bfs([c], "b", []));