Min Stack

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Min Stack — Nvidia interview prep · Stack

Classic interview problem #155.

Input (stdin)

Line 1: n ops\nNext lines: push x | pop | top | getMin

Output (stdout)

Output for each query line (top/getMin)

Your program must read from stdin and write the answer to stdout (no extra debug text).

Examples

Sample

Input

5
push -2
push 0
getMin
pop
top

Output

-2

Static hints

Input format: Line 1: n ops\nNext lines: push x | pop | top | getMin
DSA Interview 150 — Stack
Problem #155
Frequently asked at Nvidia
Stack

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Stuck? Get a nudge — not the answer

Progressive help: Nudge → Guide → Approach. Full solution stays behind the Solution tab.

Your solution

Editor is open — no login wall to practice.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

class Program
{
    static int[] Ria(string line = null)
    {
        line ??= Console.ReadLine();
        if (string.IsNullOrWhiteSpace(line)) return Array.Empty<int>();
        return line.Trim().Split(new[] { ' ', ',', '\t' }, StringSplitOptions.RemoveEmptyEntries)
            .Select(int.Parse).ToArray();
    }
    static string[] Rsa()
    {
        int n = int.Parse(Console.ReadLine());
        var arr = new string[n];
        for (int i = 0; i < n; i++) arr[i] = Console.ReadLine();
        return arr;
    }
    static void W(params object[] parts) => Console.WriteLine(string.Join(" ", parts));
    static void Wb(bool v) => Console.WriteLine(v ? "true" : "false");
    static void Wi(int v) => Console.WriteLine(v);
    static void Ws(string v) => Console.WriteLine(v);

static void Main()
    {
        // Read from stdin (see problem statement for format)
        // Line 1: n ops\nNext lines: push x | pop | top | getMin

}
}

Ready — edit the code above and click Run or Submit.

Official solution

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

class Program
{
    static int[] Ria(string line = null)
    {
        line ??= Console.ReadLine();
        if (string.IsNullOrWhiteSpace(line)) return Array.Empty<int>();
        return line.Trim().Split(new[] { ' ', ',', '\t' }, StringSplitOptions.RemoveEmptyEntries)
            .Select(int.Parse).ToArray();
    }
    static string[] Rsa()
    {
        int n = int.Parse(Console.ReadLine());
        var arr = new string[n];
        for (int i = 0; i < n; i++) arr[i] = Console.ReadLine();
        return arr;
    }
    static void W(params object[] parts) => Console.WriteLine(string.Join(" ", parts));
    static void Wb(bool v) => Console.WriteLine(v ? "true" : "false");
    static void Wi(int v) => Console.WriteLine(v);
    static void Ws(string v) => Console.WriteLine(v);

    static void Main()
    {
int n = int.Parse(Console.ReadLine());
var st = new Stack<int>();
var mins = new Stack<int>();
for (int i = 0; i < n; i++) {
    var parts = Console.ReadLine().Split(' ');
    if (parts[0] == "push") {
        int x = int.Parse(parts[1]);
        st.Push(x);
        mins.Push(mins.Count == 0 ? x : Math.Min(x, mins.Peek()));
    } else if (parts[0] == "pop") { st.Pop(); mins.Pop(); }
    else if (parts[0] == "top") Wi(st.Peek());
    else if (parts[0] == "getMin") Wi(mins.Peek());
}
    }
}

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Explanation

Step 1 / 1

Nvidia interview context: Min Stack is a Medium Stack problem — Monotonic stack or bracket matching — watch for O(n) single-pass solutions.

Use the animation above to step through each move before writing code.

Pattern: Stack

Read from stdin, write to stdout. Classic interview problem #155.

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