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<title>算法总结</title>
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<div>算法总结</div>
<script>
//阶乘
function factorial(num){
if(num<0){
return -1;
}else if(num==0 || num==1){
return 1
}else{
return num*factorial(num-1);
}
}
console.log(factorial(5));
//正念反念都一样
function palindrome(text){
var retText = text.replace(/[^a-zA-z0-9]/g,"").toLowerCase().split("");
return retText.join()==retText.reverse().join()?true:false;
}
console.log(palindrome("never odd or even"));
//找出最长的单词
function findLongWord(str){
var new_str = str.split(" ");
var new_arr = [];
for(var i=0;i<new_str.length;i++){
new_arr.push(new_str[i].length);
}
return new_arr.sort(function(a,b){
return b-a
})[0]
}
console.log(findLongWord("The quick brown fox jumped over the lazy dog"));
//选择排序算法（找到数组最大值，和索引。最大值添加到新数组的第一位，删除老数组最大的索引位）
function sortawait(arr){
var str_arr = [...arr];
var new_arr = [];
for(var i=0;i<str_arr.length;i++){
var max = Math.max.apply(null,arr);
var index = arr.indexOf(max);
new_arr.push(max)
arr.splice(index,1);
}
return new_arr;
}
console.log(sortawait([10,3,8,4,6,5]));
//冒泡排序算法（两两对比，前面和后面相互比较，大的数往后移动）；
function bubbleSort(arr){
var len = arr.length;
for(var i=0;i<len;i++){
for(var j=0;j<len-1-i;j++){ //每次循环一次，最后一位定时最大的，也就没有必要在拿出来比较
if(arr[j]>arr[j+1]){
var fontValue = arr[j];
arr[j]=arr[j+1];
arr[j+1]=fontValue;
}
}
}
}
console.log(sortawait([10,3,8,4,6,5]));
//英文首字母大写
function titleCase(title){
var arr_title = title.toLowerCase().split(" ");
for(var i=0;i<arr_title.length;i++){
arr_title[i]=arr_title[i].replace(arr_title[i].charAt(0),arr_title[i].charAt(0).toUpperCase())
}
return arr_title.join(" ");
}
console.log(titleCase("I'm a little tea pot"));
//二维数组返回最大的数
function largestOfFour(muitArr){
var new_arr = [];
for(var i=0;i<muitArr.length;i++){
muitArr[i].sort(function(a,b){
return b-a
});
new_arr.push(muitArr[i][0]);
}
return new_arr;
}
console.log(largestOfFour([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]));
//模拟repeat添加重复字符
function repeat(str,timer){
var new_str = str || "";
var timer = timer || 0;
for(var i=0;i<timer-1;i++){
new_str+=str;
}
return new_str;
}
console.log(repeat("abc", 3));
//截取字符串，多余的省略号(这里还是有缺陷的，2个数字或英文字符位==1个中文字符位=>导致长度不一)
function interceptChart(value,number){
var interValue = value.substring(0,number);
if(value.length>number){
interValue=interValue+"...";
}
return interValue;
}
console.log(interceptChart("天才是1%的灵感,加上99%的汗水,但那1%的灵感才是最重要的",5));
//按指定大小切割数组
function chunk(arr,len){
var new_arr = [];
var index=0;
for(var i=0;i<arr.length;i++){
if(i!=0 && i%len==0){
new_arr.push(arr.slice(index,i));
index=i;
}
}
new_arr.push(arr.slice(index,arr.length));
return new_arr;
}
console.log(chunk(["a", "b", "c", "d","e","f","g","h"], 3));
//数组去重
function removeArray(arr){
var new_arr = [];
for(var i=0;i<arr.length;i++){
if(new_arr.indexOf(arr[i])==-1){
new_arr.push(arr[i]);
}
}
return new_arr;
}
console.log(removeArray(["他","它","他","她","he","它","her",'he',"he"]));
//ES6去重
function eSixRemoveArray(arr){
var set_arr = new Set(arr); //实例化后的数组转化成set类型并成功去重
return Array.from(set_arr); //数据set类型转化成数组类型
}
console.log(eSixRemoveArray(["他","它","他","她","he","它","her",'he',"he"]));
//模拟迭代器（封装遍历，对象/数组/map/set都可以通过它来遍历）
function dieEach(array,callback){
if(Object.prototype.toString.call(array) === '[object Array]'){
for(var i=0;i<array.length;i++){
callback(array[i],i)
}
}else if(Object.prototype.toString.call(array) === '[object Map]'){
for(var key of array.keys()){
callback(array.get(key),key)
}
}else if(Object.prototype.toString.call(array) === '[object Set]'){
var setArr = Array.from(array);
for(var i=0;i<setArr.length;i++){
callback(setArr[i],i)
}
}else{
for(var key in array){
callback(array[key],key)
}
}
}
// dieEach([3,4,5,6],function(item,i){
// console.log(item);
// })
// dieEach({"name":"zhuyang","age":14,"sex":"男"},function(item,i){
// console.log(item);
// })
// var dieMap = new Map();
// dieMap.set("a",1);
// dieMap.set("b",2);
// dieEach(dieMap,function(item,i){
// console.log(item);
// })
var dieSet = new Set([1,2,3,4,5,6]);
dieEach(dieSet,function(item,i){
console.log(item);
})
//实现slice截取功能
Array.prototype.dieSlice = function(){
var start = arguments[0] || 0;
var end = arguments[1] || this.length;
var newArray = [];
for(var i=start;i<end;i++){
newArray.push(this[i])
}
return newArray;
}
console.log([1,2,3,4,5,6,7,8,9].dieSlice(4,6));
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