Add weight for weight

Author: dwqs

codewars/201807/weight-for-weight.md

@@ -0,0 +1,90 @@
+
+## Description
+
+My friend John and I are members of the "Fat to Fit Club (FFC)". John is worried because each month a list with the weights of members is published and each month he is the last on the list which means he is the heaviest.
+
+I am the one who establishes the list so I told him: "Don't worry any more, I will modify the order of the list". It was decided to attribute a "weight" to numbers. The weight of a number will be from now on the sum of its digits.
+
+For example `99` will have "weight" `18`, `100` will have "weight" `1` so in the list `100` will come before `99`. Given a string with the weights of FFC members in normal order can you give this string ordered by "weights" of these numbers?
+
+### Examples
+`"56 65 74 100 99 68 86 180 90"` ordered by numbers weights becomes: `"100 180 90 56 65 74 68 86 99"`
+
+When two numbers have the same "weight", let us class them as if they were strings and not numbers: `100` is before `180` because its "weight" (1) is less than the one of `180` (9) and `180` is before `90` since, having the same "weight" (9) it comes before as a string.
+
+All numbers in the list are positive numbers and the list can be empty.
+
+### Notes
+* it may happen that the input string have leading, trailing whitespaces and more than a unique whitespace between two consecutive numbers
+* Don't modify the input
+* For C: The result is freed.
+
+**Kata's link**: [Valid Parentheses](https://www.codewars.com/kata/weight-for-weight)
+
+## Best Practices
+
+**First:**
+```js
+function orderWeight(strng) {
+ return strng
+ .split(" ")
+ .map(function(v) { 
+ return {
+ val: v,
+ key: v.split("").reduce(function(prev, curr) {
+ return parseInt(prev) + parseInt(curr);
+ }, 0)
+ };
+ })
+ .sort(function(a, b) {
+ return a.key == b.key 
+ ? a.val.localeCompare(b.val)
+ : (a.key - b.key);
+ })
+ .map(function(v) {
+ return v.val;
+ })
+ .join(" ");
+}
+```
+
+**Second:**
+```js
+function orderWeight(strng) {
+ const sum = (str)=>str.split('').reduce((sum,el)=>(sum+(+el)),0);
+ function comp(a,b){
+ let sumA = sum(a);
+ let sumB = sum(b);
+ return sumA === sumB ? a.localeCompare(b) : sumA - sumB;
+ };
+ return strng.split(' ').sort(comp).join(' ');
+}
+```
+
+## My solutions
+```js
+function sumOfWeightDigits (weight) {
+ return ('' + weight).split('').reduce((prev, next) => {
+ return ~~prev + ~~next;
+ }, 0);
+}
+
+function compare (a, b) {
+ return a < b ? -1 : 1;
+}
+
+function orderWeight(strng) {
+ // your code
+ const weights = strng.trim().split(/\s{1,}/).map((v, i) => {
+ return {
+ key: '' + v,
+ val: sumOfWeightDigits(v)
+ }
+ }).sort((a, b) => {
+ const diff = a.val - b.val;
+ return diff === 0 ? compare(a.key, b.key) : diff;
+ });
+
+ return weights.map(item => item.key).join(' ');
+}
+```

readme.md

@@ -8,6 +8,7 @@ Here is my codewars homepage: https://www.codewars.com/users/dwqs.
 ## Lists
 ### 2018-07
 * [Valid Parentheses](codewars/201807/valid-parentheses.md)
+* [Weight for weight](codewars/201807/weight-for-weight.md)
 
 ### 2017-02
 * [Regex Password Validation](codewars/git/regex-password-validation.md)