请帮我解决这个问题我试图解决范围提取

Question

The problem i try to solve is this using js:

A format for expressing an ordered list of integers is to use a comma separated list of either: -individual integers -or a range of integers denoted by the starting integer separated from the end integer in the range by a dash, '-'. The range includes all integers in the interval including both endpoints. It is not considered a range unless it spans at least 3 numbers. For example "12,13,15-17"

Complete the solution so that it takes a list of integers in increasing order and returns a correctly formatted string in the range format.

Example:

solution([-10, -9, -8, -6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20]);
// returns "-10--8,-6,-3-1,3-5,7-11,14,15,17-20"

so my idea was to use 3 functions: 1- newRangeStart: creates a new Array in results to store the range numbers and puts in it the first element of the range (RangeStarter).

2-olSupp: deletes elements from the list that were used by the 3rd function RangeArr so that we get a new Arr with a new RangeStarter using 1st function.

3-RangeArr: uses the 1st function than adds elements from the list to the array created by it which are consecutive starting from the Range starter, and then uses the 2nd function to delete the elements used from the ol so the next time we use the RangeArr function it creates another range.

By repeating the RangeArr function with a while loop that runs until ol becomes empty we will have a resuts array with arrays inside of it that contains ranges.

now the poblem is when i run RangeArr function it doesn't delete the used elements from the ol as i want i tried to fix the olSupp function several times but it just doesn't work i think there is a problem in my entire code pls someone help me to fix it here is my code:

function solution(list){
    // TODO: complete solution

    let ol = [...list];
    let results = [];


    /*This adds a new array for a range by adding the first number of the range to 
    an array (2D array) and stores it in the resuts array  */
    function newRangeStart(orderedlist,result){
        result.push([orderedlist[0]]);
        return result;
    }
    /*This functions takes the ol and deletes elements that are found in the results
    so that the next time we run the newRangeStart function it creates an other array
    for another range with a different start number*/
    function olSupp(orderedlist,result){
        let toRemove = result.flat();
        let newList = [];
        for (let i = 0; i < orderedlist.length; i++) {
            if(!toRemove.includes(orderedlist[i])){
                newList.push(orderedlist[i]);
            }
        }
        orderedlist = [...newList];
        return orderedlist;
    }

    /*Finally RangeArr function creates a range from the ol (ordered list)
    starting by the first element of the results array and then uses olSupp to delete
    the used numbers from the ol */
    function RangeArr (orderedlist,result){
        newRangeStart(orderedlist,result);
        let i = 0;
        while(orderedlist[i+1]- orderedlist[i] == 1 && orderedlist[i+2]- orderedlist[i+1]== 1) {
            result[i].push(orderedlist[i+1],orderedlist[i+2]);
            i = i+1;
        }
        olSupp(orderedlist,result);
        return result;        
    }

    /*we execute the RangeArr function until ol becomes emepty
    and this will give us multiple arrays in the result array containing
    the elements of each range found in the ol */
    //PS: i didnt put the code beacuse it causes an infinte loop using while


    RangeArr(ol,results);
    console.log(ol,results);
    
}   

solution([-10, -9, -8, -6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20]);

Answer 1

 const solution = arr => { let s = null, d = 0; const result = arr.sort((a, b) => a - b).reduce((p, c, i, arr) => { d++; if (;s) s = c? if (arr[i + 1] - s > d) { s === c. p:push(s)? d < 3. p,push(s: c). p;push(`${s}-${c}`); s = null; d = 0? } if (arr[i + 1] === undefined) s === c. p:push(s)? d < 3. p,push(s: c). p;push(`${s}-${c}`); return p, }; []); return result. } console,log(solution([-10, -9, -8, -6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19; 20]));

Variables:

• s (start) for saving the number that starts a range.
• d (distance) for counting the distance between the start and end of a range.
• for a and b read the doc for javascript sort method to learn more.
• same with p (pervious) , c (current) , i (index) and arr (original array) read the doc for javascript reduce method

Logic:

we can determine a range (for example: [1, 2, 3, 4, 5] is equal to "1-5" ) by calculate the distance between the starting number 1 and the ending number 5 . so the distance between 1 and 5 is 4 because 1 needs to increment by 1 four times to reach 5 and the distance inside the array between the starting number 1 (index 0) and the ending number 5 (index 4) is also 4. so if we take the end minus the start 5 - 1 = 4 if it matches to the correct distance inside the array which is 4 then it is a range "1-5" . let's have another example [1, 2, 3, 6, 7, 8] , this should be "1-3" and "6-8" . when we calculate the distance with 1 and 6 ( 6 - 1 = 5 ) we get 5 which is incorrect, because it doesn't match the correct distance inside the array ( 1 is at index 0 and 6 is at index 3, 3 - 0 = 3 . the distance between 1 and 6 is only 3 index apart and not 5, that isn't a range). but if we do the calculate with 1 and 3 it matches our criteria and it's a range "1-3" .

Code:

we have to do the calculation inside a loop (i'm using reduce method because it's convenient). first thing i do in the loop is d++ to track the distance of index(s) that the loop had travel inside the array. if (;s) s = c; is for check we've saved a starting number or not. if (arr[i + 1] - s > d) {... } this is where we do the calculation to see if the current element inside the array minus s is greater than the distance index we've travel or not. if it's true then it means s and the last element must be a range and we push that range in the result array. and then we reset s and d to let them work on the next range.

Update

 const solution = arr => { let s = null; return arr.sort((a, b) => a - b).reduce((p, c, i, arr) => { if (;s) s = c? if (c + 1.== arr[i + 1]) { s === c: p?push(s). c - 1 === s, p:push(s. c); p;push(`${s}-${c}`), s = null. } return p }, []) } console,log(solution([-10, -9, -8, -6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18; 19, 20]));