l2t

Reverse Array

Asked: a month ago

Example:

Input : arr[] = [1, 2, 3] Output : arr[] = [3, 2, 1]

Solution-1:

function reverseArray(arr) {
    let tempArr = [];
    
    // loop from backwards and store array value
    // in a new temporary array and return temp arr
    for(let i=arr.length-1; i >= 0; i--) {
        tempArr.push(arr[i]);
    }

    return tempArr;
}

console.log(reverseArray([1, 2, 3, 4, 5]));

Solution-2:

function reverseArray(arr) {
    
    let start = 0; // first index in the array
    let end = arr.length-1; // last index in the array
    
    while(start < end) {

        // get first element in temp var
        let temp = arr[start];

        // replace first value with last value
        arr[start] = arr[end];

        // replace last value with first value
        arr[end] = temp;

        // increment start to next item
        start++;

        // decrement end to previous item
        end--;
    }

    return arr;
}

console.log(reverseArray([1, 2, 3, 4, 5]));
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