codewars练习（javascript）-2021/3/12

codewars-js练习

2021/3/12

github 地址

my github地址，上面有做的习题记录，不断更新…

【1】<7kyu>【Printer Errors】

a to m.

example：

s="aaabbbbhaijjjm"
error_printer(s) => "0/14"

s="aaaxbbbbyyhwawiwjjjwwm"
error_printer(s) => "8/22"

solution

<script type="text/javascript">
    function printerError(s) {
        console.log(s)
        var arr = s.match(/[n-z]/ig)
        var len;
        if(arr == null) len = 0
        else len = arr.length
        return len + '/' + (s.length)
    }
    // 验证
    // console.log(printerError("aaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbmmmmmmmmmmmmmmmmmmmxyz"));//"3/56"
    console.log(printerError('kkkwwwaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbmmmmmmmmmmmmmmmmmmmxyz'));//'6/60'
    console.log(printerError('aaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbmmmmmmmmmmmmmmmmmmm'));//0
</script>

function printerError(s) {
  return `${s.replace(/[a-m]/ig, '').length}/${s.length}`;
}

【2】<7kyu>【Sum of Cubes】

Write a function that takes a positive integer n, sums all the cubed values from 1 to n, and returns that sum.

example：

sumCubes(2) // 9
// sum of the cubes of 1 and 2 is 1 + 8

solution

<script type="text/javascript">
    function sumCubes(n){
        // console.log(n) 
        var sum = 0;
        for(var i =0;i<=n;i++){
            sum = sum + Math.pow(i,3);
        }   
        return sum
    }
    // 验证
    console.log(sumCubes(1));//1
    console.log(sumCubes(2));//9
    console.log(sumCubes(3));//36
</script>

【3】<7kyu>【Reverse the bits in an integer】

Write a function that reverses the bits in an integer.

For example, the number 417 is 110100001 in binary. Reversing the binary is 100001011 which is 267.

example：

417 //267.

solution

<script type="text/javascript">
    function reverseBits (n) {
        console.log(n)
        var temp = n.toString(2).split('').reverse().join('');
        return parseInt(temp,2);
    }
    // 验证
    console.log(reverseBits(417));//267
</script>