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  1. Queue using Two Stacks
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Queue using Two Stacks

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253 Discussions

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  • seanjennings976
     + 0 comments

    My C# solution

    Spent ages trying to find input from args when it actually comes from Console.ReadLine. Had to read up on two stacks before attempting question. Was failing a few test cases on time limit until I switched from using linq .Any() to checking .Count > 0

    class Solution {
    static void Main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution */
        (Stack<int> stack1, Stack<int> stack2) = (new(), new());

        var numberOfInputs = Int32.Parse(Console.ReadLine()!);
        
        for (int _ = 0; _ < numberOfInputs; _++)
        {
            var arg = Console.ReadLine()!.Split();
            switch(arg[0])
            {
                case "1":
                    var enqueueValue = Int32.Parse(arg[1]);
                    stack1.Push(enqueueValue);
                    continue;
                case "2":
                case "3":
                    if (stack2.Count == 0) 
                    {
                        while(stack1.Count > 0)
                        {
                            stack2.Push(stack1.Pop());
                        }
                    }
                    if (arg[0] == "3")
                    {
                        Console.WriteLine(stack2.Count > 0 ? stack2.Peek() : stack1.Peek());
                        continue; 
                    }
                    stack2.Pop(); 
                    continue;
                default:
                  throw new ArgumentException("Ffs Hackerrank");
            }
        }
    }
}

  • waynercoppock
     + 1 comment

    uh, does this even work on C#? It's not passing me any args

  • evanmico222
     + 0 comments

    js answer using solely regex to parse the input (and actually 2 'stacks'):

    function processData(input) {
    let frontStack = new Array();
    let tailStack = new Array();
    let regex = /(?<=\n)(?<type>\d)\s*?(?<value>\d*)(?=(\n|$))/g;
    let inputObjArr = [...input.matchAll(regex)].map((result) => (
        {
            'type': Number(result.groups.type),
            'value': result.groups.value
        }
    ));
    inputObjArr.forEach((inputObj) => {
        switch(inputObj.type){
            case 1: {
                tailStack.push(inputObj.value);
                break;   
            }
            case 2: {
                if(frontStack.length === 0){
                    while(tailStack.length > 0){
                        frontStack.push(tailStack.pop());
                    }
                }
                frontStack.pop();
                break;
            }
            case 3: {
                if(frontStack.length === 0){
                    while(tailStack.length > 0){
                        frontStack.push(tailStack.pop());
                    }
                }
                console.log(frontStack.at(-1))
                break;
            }
        }
    })
}

  • mohamedhari317
     + 0 comments
    p=[]
for _ in range(int(input())):
    l=list(map(int,input().split()))
    if l[0]==1:
        p.append(l[1])
    if l[0]==2:
        p.pop(0)
    if l[0]==3:
        print(p[0])

  • arieldelgrande
     + 0 comments

    My Solution in Javascript also works with TypeScript:

    function processData(input) {

    const query = input.split('\n').slice(1)

const answer = []

for(let i = 0; i < query.length; i++) {
    if(query[i].charAt(0) === '1') {
        const [index, number] = query[i].split(' ')
        answer.push(number) 
    }
    if(query[i].charAt(0) === '2') {
        answer.shift()
    }

    if(query[i].charAt(0) === '3') {
        console.log(answer[0])
    }
}

    }