Quizes

zig-zag.ts

// Given an array of DISTINCT elements, rearrange the elements of array in zig-zag fashion in O(n) time.
// The converted array should be in form a < b > c < d > e < f. 

// Example:
// Input: arr[] = {4, 3, 7, 8, 6, 2, 1} 
// Output: arr[] = {3, 7, 4, 8, 2, 6, 1}

// Input: arr[] = {1, 4, 3, 2} 
// Output: arr[] = {1, 4, 2, 3}

function zigzag(inputNumbers: number[]) {
    const outputNumbers = [...inputNumbers];
    let currIndex = 0;
    for (const number of outputNumbers) {
        const isEvenIndex = currIndex % 2 === 0;
        const nextIndex = currIndex+1;
        const nextNumber = outputNumbers[nextIndex];
        if ((isEvenIndex && number > nextNumber) || (!isEvenIndex && number < nextNumber)) {
            outputNumbers[currIndex] = nextNumber;
            outputNumbers[nextIndex] = number;
        }
        currIndex++;
    }
    return outputNumbers;
}

const input = [4, 3, 7, 8, 6, 2, 1];
const output = zigzag(input);
console.log({ input, output });