有趣的算法2

2017-04-09
几个算法

再这篇文章里，只是暂存最近玩的freecodecamp的中级算法题目，锻炼下思维，熟悉下最基础的方法，有时候写点原生js可以解决很多很多问题，且性能更高，不多说，上题目：
//Sum All Numbers in a Range
    function sumAll(arr) {
        var ary = [];
        var max = Math.max.apply(null,arr);
        var min = Math.min.apply(null,arr);
        function sumFun(max,min) {
            for(var i = 0;i<(max-min+1);i++){
                ary.push(min+i);
            }
            var value = ary.reduce(function (pre,cur) {return pre+cur ; });
            return value;
        }
        return sumFun(max,min);
    }
    //Diff Two Arrays
    function diff(arr1, arr2) {
        var newAry = [];
        var curAry;
        function isEqual(a) {
            var value = curAry.some(function (b) {
                return a===b;
            });
            return !value;
        }
        curAry = arr1;
        newAry = newAry.concat(arr2.filter(isEqual));
        curAry = arr2;
        newAry = newAry.concat(arr1.filter(isEqual));
        return newAry;
    }
   // Roman Numeral Converter
    function convert(num) {
        var nums = [1000,900,500,400,100,90,50,40,10,9,5,4,1];
        var romans =["m","cm","d","cd","c","xc","l","xl","x","ix","v","iv","i"];
        var str = '';
        nums.forEach(function (item, index, arr) {
            while(num>=item){
                str+=romans[index];
                num-=item;
            }
        });
        return str.toUpperCase();
    }
    //Where are you
    function where(collection, source) {
        var arr = [];
        var keys = Object.keys(source);
        arr = collection.filter(function (item) {
            return keys.every(function (key) {
                return item.hasOwnProperty(key) && item[key]===source[key];
            });
        });
        return arr;
    }
    //find and replace
    function myReplace(str, before, after) {
        //获取第一位是否大小写，然后转换为after的首字母
        before.search(/^[A-Z]/)>-1? (after = after.replace(/^\w/,function (item) {return  item.toUpperCase();})):(after = after.replace(/^\w/,function (item) {return item.toLowerCase();}));
        var ary = str.split(" ");
        var index = ary.indexOf(before);
        ary.splice(index,1,after);
        str = ary.join(" ");
        return str;
    }
    function translate(str) {
    var yuanArr=["a","e","i","o","u","A","E","I","O","U"];
    var index=0;
    var result="";
    var word1="";
    var word2="";
    for(var i=0;i<str.length;i++){
        if(yuanArr.indexOf(str[i])>-1){
            index=i;
            break;
        }
    }
    if(index>0){
        word1=str.substr(0,index);
        word2=str.substr(index,str.length-index);
        result=word2+word1+"ay";
    }else if(index===0){
        result=str+"way";
    }
    return result;
    }
    //DNA Pairing
    function pair(str) {
        var ary = [];
        var strTemp = "";
        str.replace(/\w/g,function (item) {
           switch (item){
               case "A":
                   strTemp = item+"T";
                   break;
               case "C":
                   strTemp = item+"G";
                   break;
               case "G":
                   strTemp = item+"C";
                   break;
               case "T":
                   strTemp = item+"A";
                   break;
               default:
                   strTemp = item;
           }
           ary.push(strTemp.split(""));
        });
        return ary;
    }
//    Missing letters
    function fearNotLetter(str) {
        var result;
        var model = "abcdefghijklmnopqrstuvwxyz".split("");
        function getIndex(str) {
            var model = "abcdefghijklmnopqrstuvwxyz".split("");
            var index = model.indexOf(str.charAt(0));
            var x ;
            for(var i = index,j=0;i<model.length,j<str.length;i++,j++){
                console.log(model[i],str[j]);
                if(model[i]!==str[j]) {
                    x = i;
                    break;
                }
            }
            return x;
        }
        return model[getIndex(str)];
    }
    //Boo who
    function boo(bool) {
        bool = bool===true||bool===false?true:false;
        // What is the new fad diet for ghost developers? The Boolean.
        return bool;
    }
    //Sorted Union
    function unite(arr1, arr2, arr3) {
        var arrCur=[];
        for(var i = 0;i<arguments.length;i++){
            arrCur = arrCur.concat([].slice.call(arguments[i]));
        }
        return arrCur.filter(function (item,index,ary) {
            return ary.indexOf(item)===index;
        });
    }
   //Convert HTML Entities
    function convert(str) {
        str = str.replace(/[&<>"']/g,function (item) {
            switch (item){
                case "&":
                    return "&amp;";
                    break;
                case "<":
                    return "&lt;";
                    break;
                case ">":
                    return "&gt;";
                    break;
                case "\"":
                    return "&quot;";
                    break;
                case "\'":
                    return "&apo";
                    break;
            }
        });
        return str;
    }
    //Spinal Tap Case
    function spinalCase(str) {
        str = str.replace(/[A-Z]/g,function (item,index) {
            if(index>0){
                return "-"+item;
            }else{
                return item;
            }
        }).toLowerCase().replace(/[\s\-_]+/g,function () {
            return "-";
        });
        return str;
    }
   //   Sum All Odd Fibonacci Numbers
    function sumFibs(num) {
        var i = 2;
        var sum = [1,1];
        while(i<=num){
            sum.push(i);
            i=sum[sum.length-1]+sum[sum.length-2];
        }
        return sum.filter(function (item) {
            return item%2 ==1;
        }).reduce(function (a,b) {
            return a+b;
        });
    }
    //Sum All Primes
    function sumPrimes(num) {
        var total = 0;
        function isPrims(number) {
            //是否为数字
            if(typeof number !== "number" ){
                return false;
            }
            //排除偶数以及2
            if(number===2 ){
                return true;
            }else if(number%2===0){
                return false;
            }
            //排除奇数可整除
            var squrRoot = Math.sqrt(number);
            for(var i = 3;i<=squrRoot;i+=2){
                if(number%i===0){
                    return false;
                }
            }
            return true;
        }
        for(var i = 2;i<=num;i++){
            if(isPrims(i)){
                console.log(i);
                total=total+i;
//                console.log(total);
            }
        }
        return total;
    }
    //Smallest Common Multiple
    function smallestCommons(arr) {
    //最小公约数
        var gcd = function(a,b){
            if(b){
                return gcd(b, a % b);
            }
            return a;
        };
        arr.sort(function (a,b) {
            return a-b;
        });
        var curAry = arr.slice(0);curAry.pop();
        for(var i = arr[0]+1;i<=arr[arr.length-1];i++){
            curAry.push(i);
        }
        return curAry.reduce(function (pre,cur) {
            return pre*cur/gcd(pre,cur);
        })
    }
    //Finders Keepers
    function find(arr, func) {
        var aryCur = arr.filter(function (item) {
           return  func(item);
        });
        return aryCur[0];
    }
    //Drop it
        function drop(arr, func) {
            var index ;
            // Drop them elements.
            for(var i = 0;i<arr.length;i++){
                if(func(arr[i])){
                    index = i;
                    break;
                }
            }
            var curAry = typeof index === "number"? arr.splice(index):[];
            return curAry;
        }
        //Steamroller
    function binaryAgent(str) {
        str = str.split(" ");
        var st = str.map(function (item) {
            return parseInt(item,2);
        });
        console.log(st);
        var str1 = "";
        for(var i = 0;i<st.length;i++){
            str1+= String.fromCharCode(st[i]);
        }
        return str1;
    }
//    Everything Be True
    function every(collection, pre) {
        var flag = collection.every(function (item) {
            return item.hasOwnProperty(pre) && item[pre];
        });
        return flag;
    }
//    Arguments Optional
    function add() {
        if(arguments.length===2 && typeof arguments[0] === "number" &&typeof arguments[1] === "number"){
            return arguments[0]+arguments[1];
        }else if(arguments.length===1 && typeof arguments[0]==="number"){
            var x = arguments[0];
            return function (y) {
                var result;
                if(typeof y === "number") {
                    return x + y;
                }
            }
        }else{
            return ;
        }
    }