本文记录了在 Codewars 上进行的 JavaScript 练习，包括建塔、字母位置替换、正数求和、BMI 计算、作业纸张计算、简单问题解决、立方体体积差、奇数筛选、字符解析、CSV 表示等题目，详细阐述了解题思路和解决方案，适合编程初学者参考学习。
文章目录
- codewars-js练习
- 2021/1/20
- github 地址
- 【1】 <6kyu>【Build Tower】
- 【2】<6 kyu>【Replace With Alphabet Position】
- 【3】<8 kyu>【Sum of positive】
- 【4】<8kyu>【Calculate BMI】
- 【5】<8kyu>【Beginner Series #1 School Paperwork】
- 【6】<8kyu>【Super Duper Easy】
- 【7】<8kyu>【Difference of Volumes of Cuboids】
- 【8】<8kyu>【Are arrow functions odd?】
- 【9】<8kyu>【Parse nice int from char problem】
- 【10】<8kyu>【CSV representation of array】
codewars-js练习
2021/1/20
github 地址
【1】 <6kyu>【Build Tower】
Build Tower by the following given argument （即 建塔）
example：
a tower of 3 floors looks like below
[
' * ',
' *** ',
'*****'
]
a tower of 6 floors looks like below
[
' * ',
' *** ',
' ***** ',
' ******* ',
' ********* ',
'***********'
]
思路：
以a tower of6 floors looks like below为例
| i | 前空格数 | *数 | 后空格数 |
|---|---|---|---|
| 0 | 5 | 1 | 5 |
| 1 | 4 | 3 | 4 |
| 2 | 3 | 5 | 3 |
| 3 | 2 | 7 | 2 |
| 4 | 1 | 9 | 1 |
| 5 | 0 | 11 | 0 |
因此：
- *数=2*i+1
- 前空格数=nFloors -i -1
- 后空格数=nFloors -i -1
solution：
<script type="text/javascript">
function towerBuilder(nFloors) {
// console.log(nFloors);
var result = [];
for(var i=0;i<nFloors;i++){
result.push(" ".repeat(nFloors-i-1)
+ "*".repeat(2*i+1)
+ " ".repeat(nFloors-i-1));
console.log(result);
}
return result;
}
// 验证
console.log(towerBuilder(1));//['*']
console.log(towerBuilder(3));//[" * "," *** ","*****"]
</script>
【2】<6 kyu>【Replace With Alphabet Position】
In this kata you are required to, given a string, replace every letter with its position in the alphabet.（即 给定一个字符串，用它在字母表中的位置替换每个字母。）
example：
alphabetPosition("The sunset sets at twelve o' clock.")
//"20 8 5 19 21 14 19 5 20 19 5 20 19 1 20 20 23 5 12 22 5 15 3 12 15 3 11"
思路：
- 将文本全部转为大写；
- 利用正则表达式将不是[A-Z]的内容替换成掉；
- 按照空格分隔放到arr数组中；
- 匹配到unicode编码，并用join连接返回。
solution：
<script type="text/javascript">
function alphabetPosition(text) {
// 将文本全部转为大写
var str = text.toUpperCase();
// 利用正则表达式将不是[A-Z]的内容替换成掉
str = str.replace(/[^A-Z]/g,'');
// 按照空格分隔放到arr数组中
var arr = str.split('');
// 匹配到unicode编码，并用join连接返回
// charCodeAt()返回指定位置的unicode编码
arr = arr.map((c) => c.charCodeAt()-64).join(' ');
// console.log(arr);
return arr;
}
// 验证
console.log(alphabetPosition("The sunset sets at twelve o' clock."));//"20 8 5 19 21 14 19 5 20 19 5 20 19 1 20 20 23 5 12 22 5 15 3 12 15 3 11"
</script>
【3】<8 kyu>【Sum of positive】
You get an array of numbers, return the sum of all of the positives ones.（即返回所有正数的和）
example：
[1,-4,7,12] => 1 + 7 + 12 = 20
solution：
<script type="text/javascript">
function positiveSum(arr) {
var length = arr.length;
if(length !=0){
var sum=0;
for(var i=0;i<length;i++){
// console.log(arr[i]);
if(arr[i]>=0){
sum +=arr[i];
// console.log(sum);
}
}
return sum;
}else{
return 0;
}
}
// 验证
console.log(positiveSum([1,2,3,4,5]));//15
console.log(positiveSum([1,-2,3,4,5]));//13
console.log(positiveSum([]));//0
</script>
</head>
【4】<8kyu>【Calculate BMI】
Write function bmi that calculates body mass index (bmi = weight /( height ^ 2)).
if bmi <= 18.5 return “Underweight”
if bmi <= 25.0 return “Normal”
if bmi <= 30.0 return “Overweight”
if bmi > 30 return “Obese”
example：
bmi(80, 1.80));//Normal
solution：
<script type="text/javascript">
function bmi(weight, height) {
console.log(weight,height);
var h = height*100;
var bmi = (weight/(Math.pow(h,2)))*10000;
// console.log(bmi);
if(bmi <=18.5){
return "Underweight";
}else if(bmi>18.5 &&bmi<=25.0){
return "Normal";
}else if(bmi>25.0 &&bmi<=30.0){
return "Overweight";
}else{
return "";
}
}
// 验证
console.log(bmi(80, 1.80));//Normal
</script>
【5】<8kyu>【Beginner Series #1 School Paperwork】
Your classmates asked you to copy some paperwork for them. You know that there are ‘n’ classmates and the paperwork has ‘m’ pages.
Your task is to calculate how many blank pages do you need. If n < 0 or m < 0 return 0.
example：
n= 5, m=5: 25
n=-5, m=5: 0
solution：
<script type="text/javascript">
function paperwork(n, m) {
if(n<0||m<0){
return 0;
}else{
return n*m;
}
}
// 验证
console.log(paperwork(5,5));//25
console.log(paperwork(-5,5));//0
</script>
【6】<8kyu>【Super Duper Easy】
Make a function that returns the value multiplied by 50 and increased by 6. If the value entered is a string it should return “Error”.
example：
problem("hello")//"Error"
problem(1)//56
solution：
<script type="text/javascript">
function problem(x){
if(typeof x=='string'){
return "Error";
}else{
return x*50+6;
}
}
// 验证
console.log(problem("hello"));//"Error"
console.log(problem(1));//56
</script>
【7】<8kyu>【Difference of Volumes of Cuboids】
In this simple exercise, you will create a program that will take two lists of integers, a and b. Each list will consist of 3 positive integers above 0, representing the dimensions of cuboids a and b. You must find the difference of the cuboids’ volumes regardless of which is bigger.
For example, if the parameters passed are ([2, 2, 3], [5, 4, 1]), the volume of a is 12 and the volume of b is 20. Therefore, the function should return 8.
example：
findDifference([3, 2, 5], [1, 4, 4]), 14
findDifference([15, 20, 25], [10, 30, 25]), 0
solution：
<script type="text/javascript">
function findDifference(a, b) {
var temp1 = 1;
var temp2 = 1;
for(var i=0;i<a.length;i++){
temp1 *=a[i];
}
for(var j=0;j<b.length;j++){
temp2 *=b[j];
}
var result = temp2-temp1;
return result>=0?result:-result;
}
// 验证
console.log(findDifference([3, 2, 5], [1, 4, 4]));//14
console.log(findDifference([15, 20, 25], [10, 30, 25]));//0
</script>
【8】<8kyu>【Are arrow functions odd?】
example：
odds([1,2,3,4,5]) // [1,3,5]
solution：
<script type="text/javascript">
function odds(values){
var result = [];
for(var i=0;i<values.length;i++){
if(values[i] % 2 !=0){
result.push(values[i]);
}
}
return result;
}
// 验证
console.log(odds([1,2,3,4,5]));//[1,3,5]
</script>
【9】<8kyu>【Parse nice int from char problem】
example：
getAge"4 years old")//44
solution：
<script type="text/javascript">
function getAge(inputString){
var arr = inputString.split(' ');
return parseInt(arr[0]);
}
// 验证
console.log(getAge("4 years old")) //4
</script>
【10】<8kyu>【CSV representation of array】
CSV representation of array==（即 创建一个返回二维数值数组的CSV表示形式的函数。）==
example：
input:
[[ 0, 1, 2, 3, 4 ],
[ 10,11,12,13,14 ],
[ 20,21,22,23,24 ],
[ 30,31,32,33,34 ]]
output:
'0,1,2,3,4\n'
+'10,11,12,13,14\n'
+'20,21,22,23,24\n'
+'30,31,32,33,34'
solution：
<script type="text/javascript">
function toCsvText(array) {
return array.join('\n');;
}
// 验证
console.log(toCsvText([
[ 0, 1, 2, 3, 45 ],
[ 10,11,12,13,14 ],
[ 20,21,22,23,24 ],
[ 30,31,32,33,34 ]
] ));
</script>
以上为自己思路供大家参考，可能有更优的思路。
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