Valid Parentheses — DSA Interview 150 · Stack
Classic interview problem #20.
Input (stdin)
Line 1: bracket string
Output (stdout)
true or false
Your program must read from stdin and write the answer to stdout (no extra debug text).
()[]{}true
| Test | Status | Details |
|---|
Ready — edit the code above and click Run or Submit.
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()
{
string s = Console.ReadLine();
var st = new Stack<char>();
var pairs = new Dictionary<char, char> { [')']='(', [']']='[', ['}']='{' };
bool ok = true;
foreach (var ch in s) {
if (ch == '(' || ch == '[' || ch == '{') st.Push(ch);
else if (!st.Any() || st.Pop() != pairs[ch]) { ok = false; break; }
}
Wb(ok && st.Count == 0);
}
}Try solving on your own first, then reveal the official answer.
Pattern: Stack
Read from stdin, write to stdout. Classic interview problem #20.