算法——查找一个ip地址数组中,出现次数最多的ip
作者:互联网
一道算法题
找出一组ip地址中,出现次数最多的ip,例:
输入
["192.168.12.32", "192.168.0.32", "192.168.12.32"]
输出
"192.168.12.32"
暴力破解法
function filterIp(ipArr) {
let maxIp = '';
let maxCount = 0;
for(let i = 0; i < ipArr.length; i++) {
let cur = ipArr[i];
let sum = 0;
for(let j = 0; j < ipArr.length; j++) {
if(cur === ipArr[j]){
sum++;
}
}
if(sum > maxCount) {
maxCount = sum;
maxIp = cur;
}
}
return maxIp;
}
console.time()
filterIp(arr)
console.timeEnd()
default: 0.9111328125 ms
哈希表
function filterIp(ipArr) {
const map = {};
for(let i = 0; i < ipArr.length; i++) {
// 如果map中存在当前ip的key值,则表示该ip已经被统计过了。
if(map[ipArr[i]]){
continue;
}
let cur = ipArr[i];
let sum = 0;
// 从 i 开始,i 之前的一定是被统计过了的
for(let j = i; j < ipArr.length; j++) {
if(cur === ipArr[j]){
sum++;
}
}
// 写入map中
map[cur] = sum;
}
let max = 0;
let maxIp= '';
for(let key in map){
if(map[key] > max){
max = map[key];
maxIp= key;
}
}
return maxIp;
}
console.time()
filterIp(arr)
console.timeEnd()
default: 0.208740234375 ms
字典树搜索
class Node {
constructor(data){
this.data = data;
}
data = '';
count = 1;
leaf = [];
addLeaf(leaf) {
this.leaf.push(leaf);
}
findLeaf(data) {
for(let i = 0; i < this.leaf.length; i++) {
if(this.leaf[i].data === data){
return this.leaf[i];
}
}
return null;
}
addCount(){
this.count++;
}
}
function createIpTree(ipArr){
// 根节点为空
let root = new Node('');
for(let i = 0; i < ipArr.length; i++){
let pointer = root;
ipArr[i].split('.').forEach(item => {
let includesLeaf = pointer.findLeaf(item);
if(includesLeaf){
includesLeaf.addCount();
pointer = includesLeaf;
} else {
let node = new Node(item);
pointer.addLeaf(node);
pointer = node;
}
})
}
return root;
}
function depthFirstSearch(pointer) {
let maxLeaf = pointer.leaf[0];
for(let i = 0; i < pointer.leaf.length; i++) {
if(pointer.leaf[i].count > maxLeaf.count){
maxLeaf = pointer.leaf[i];
}
}
return maxLeaf;
}
function filterIp(ipArr){
// 创建字典树
const ipTree = createIpTree(ipArr);
// 深度优先搜索字典树,找出每个节点 count 最大的叶子,向下寻找
let pointer = ipTree;
let strArr = [];
while(pointer.leaf.length) {
let maxLeaf = depthFirstSearch(pointer);
pointer = maxLeaf;
strArr.push(maxLeaf.data);
}
return strArr.join('.');
}
console.time()
filterIp(arr)
console.timeEnd()
tree: 0.26220703125 ms
字典树居然没有哈希表快?????
哈希表我可能用的不太好,我感觉还有优化方法,不过没有深入去想了。
可能还有别的方法,不过我暂时就想到这三个了。
标签:ipArr,leaf,++,ip,length,算法,查找,let,pointer 来源: https://blog.csdn.net/weixin_48003149/article/details/120786905