Card Sorter Queue Balance

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The library’s registration desk uses a two-sided card sorter for membership applications. In Card Sorter Queue Balance, you’re given a series of card IDs. Your task is to divide them into two queues: even-numbered IDs and odd-numbered IDs. This keeps the intake flow balanced for the staff!

The "secret sauce" is Parity Partitioning. You iterate through the input and use the modulo operator (% 2) to determine if a card belongs in the even or odd group. Crucially, each queue must maintain its original "arrival order" from the source. Returning these two lists as a pair providing a clean split for the desk team. This simple routine helps prevent bottlenecks and keeps the library's rush moving at a steady pace. It’s a great way to practice data separation and index management in one go!

Because this is a counting/optimization-style challenge, dynamic programming is usually the safest approach: define what each index or state means, initialize valid base states, and make transitions explicit. If the problem uses modulo arithmetic, apply modulo at every accumulation step so large intermediate totals never corrupt the final answer.

Examples

Example 1

Input

cards = [5,2,9,7], operations = ["deposit","rotate","deposit","deposit"]

Output

[5,9,7,2]

Explanation

The machine deposits 5, rotates to send 2 to the back, deposits 9, then deposits 7; the remaining queue holds only 2.

Example 2

Input

cards = [4,1,3], operations = ["rotate","deposit","deposit"]

Output

[1,3,4]

Explanation

After rotating, the queue becomes [1,3,4]; depositing twice produces [1,3], leaving [4] in the queue.

Example 3

Input

cards = [8,6], operations = ["deposit","deposit"]

Output

[8,6]

Explanation

Both cards move directly to the output pile.

Algorithm Flow

Recommendation Algorithm Flow for Card Sorter Queue Balance - Budibadu

Best Answers

java

import java.util.*;
class Solution {
    public Object card_sorter_queue_balance(Object input) {
        Object[] args = (Object[]) input;
        int[] cards = (int[]) args[0];
        String[] ops = (String[]) args[1];
        
        LinkedList<Integer> q = new LinkedList<>();
        for (int c : cards) q.add(c);
        ArrayList<Integer> out = new ArrayList<>();
        
        for (String op : ops) {
            if (q.isEmpty()) break;
            if (op.equals("deposit")) {
                out.add(q.removeFirst());
            } else if (op.equals("rotate")) {
                q.add(q.removeFirst());
            }
        }
        while (!q.isEmpty()) out.add(q.removeFirst());
        
        int[] res = new int[out.size()];
        for (int i = 0; i < out.size(); i++) res[i] = out.get(i);
        return res;
    }
}

javascript

function card_sorter_queue_balance(params) {
    const [cards, operations] = params;
    const queue = [...cards];
    const output = [];
    
    for (const op of operations) {
        if (queue.length === 0) break;
        if (op === "deposit") {
            output.push(queue.shift());
        } else if (op === "rotate") {
            queue.push(queue.shift());
        }
    }
    
    return [...output, ...queue];
}

php

<?php
function card_sorter_queue_balance($params) {
    list($cards, $operations) = $params;
    $queue = $cards;
    $output = [];
    
    foreach ($operations as $op) {
        if (empty($queue)) break;
        if ($op === "deposit") {
            $output[] = array_shift($queue);
        } elseif ($op === "rotate") {
            $queue[] = array_shift($queue);
        }
    }
    
    return array_merge($output, $queue);
}

python

from typing import List

def card_sorter_queue_balance(cards_and_ops):
    cards, operations = cards_and_ops
    queue = list(cards)
    output = []
    
    for op in operations:
        if not queue:
            break
        if op == "deposit":
            output.append(queue.pop(0))
        elif op == "rotate":
            queue.append(queue.pop(0))
    
    return output + queue

rust

fn card_sorter_queue_balance(cards: Vec<i32>, operations: Vec<String>) -> Vec<i32> {
    let mut queue: std::collections::VecDeque<i32> = cards.into_iter().collect();
    let mut output = Vec::new();
    
    for op in operations {
        if queue.is_empty() {
            break;
        }
        if op == "deposit" {
            if let Some(card) = queue.pop_front() {
                output.push(card);
            }
        } else if op == "rotate" {
            if let Some(card) = queue.pop_front() {
                queue.push_back(card);
            }
        }
    }
    
    output.extend(queue);
    output
}

typescript

function card_sorter_queue_balance(params) {
    const [cards, operations] = params;
    const queue = [...cards];
    const output = [];
    
    for (const op of operations) {
        if (queue.length === 0) break;
        if (op === "deposit") {
            output.push(queue.shift());
        } else if (op === "rotate") {
            queue.push(queue.shift());
        }
    }
    
    return [...output, ...queue];
}

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Card Sorter Queue Balance

Examples

Algorithm Flow

Best Answers

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