Question

How to rearrange an array and set arr[i] to arr[arr[index]] to index in JavaScript

Answer 1

function rearrange_array(arr) {
	let size = arr.length;
    
    for (let i = 0; i < size; i++)
        arr[i] += (arr[arr[i]] % size) * size;
 
    for (let i = 0; i < size; i++)
        arr[i] = Math.floor(arr[i] / size);
}
 

const arr = [3, 5, 0, 2, 1, 4];

// arr[arr[0]] = 2 -> arr[0] = 2
// arr[arr[1]] = 4 -> arr[1] = 4
// arr[arr[2]] = 3 -> arr[2] = 3
// arr[arr[3]] = 0 -> arr[3] = 0
// arr[arr[4]] = 5 -> arr[4] = 5
// arr[arr[5]] = 1 -> arr[5] = 1
 
rearrange_array(arr);
 
console.log(arr);
 
     
     
/*
run:
 
[2, 4, 3, 0, 5, 1]
          
*/

 

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