二叉树的搜索分为深度优先搜索和广度优先搜索。本文中主要记录本人对两种搜索的理解。 深度优先搜索:沿着节点的一条边进行搜索,一直到底,找不到后再返回根节点开始从另一条路线进行搜索。上图二叉树的深度优先搜索路线是:A-B-D-A-B-E......直到找到搜索元素才结束。对于深度优先搜索通过代码实现如下:
function Node(value) {
this.value = value;
this.left = null;
this.right = null;
}
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");
var g = new Node("g");
a.left = c;
a.right = b;
b.left = d;
b.right = e;
c.left = f;
c.right = g;
function deepSearch(root, target) {
if (root == null) return false;
if (root.value == target) return true;
var left = deepSearch(root.left, target);
var right = deepSearch(root.right, target);
return left || right;
}
console.log(deepSearch(a, 'h'));
广度优先搜索可以理解为层级搜索,一层一层的查找,在顶层找不到后向下一层进行查找,一层一层向下搜索,知道找到为止。上图二叉树的广度搜索路线是:A-B-C-D-E-F-G.对于广度优先搜索的代码实现如下所示:
function Node(value) {
this.value = value;
this.left = null;
this.right = null;
}
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");
var g = new Node("g");
a.left = c;
a.right = b;
b.left = d;
b.right = e;
c.left = f;
c.right = g;
function f1(rootList,target){
if (rootList == null || rootList.length == 0) return false;
var childList = [];//当前层所有节点的子节点,都在这个list中,这样传入下一层级的时候,就可以遍历整个层级的节点。
for (var i = 0; i < rootList.length; i++) {
if (rootList[i] !== null && rootList[i].value == target) {
return true;
} else {
childList.push(rootList[i].left);
childList.push(rootList[i].right);
}
}
return f1(childList,target);
}
console.log(f1([a],'e'));