[英]Testing if Parenthesis are balanced, (a{[]b({})}c)[] returns false, but should be true
这段代码的重点是测试每组字符串中的括号是否平衡。 有 12 个测试必须全部通过,目前,我有 11 个在工作,但是最后一个不起作用。 目前,我有三个静态布尔值,它们阐明了括号的分类,以及它们是否匹配。
private static bool IsOpeningParenthesis(char c)
{
return c == '(' || c == '[' || c == '{';
}
private static bool IsClosingParenthesis(char c)
{
return c == ')' || c == ']' || c == '}';
}
private static bool Matches(char a, char b)
{
return (a == '(' && b == ')') || (a == '[' && b == ']') ||
(a == '{' && b == '}');
}
下面,我有实际检查它们是否匹配的 bool,这就是我的错误所在。
public static bool IsBalanced(string s)
{
Stack<char> myStack = new Stack<char>();
foreach (char c in s)
{
if (IsOpeningParenthesis(c))
{
myStack.Push(c);
}
if (IsClosingParenthesis(c))
{
if (myStack.Count == 0) //takes care of closing parenthesis before adding char d
{
return false;
}
char d = myStack.Pop();
if (c == d)
{
return true;
}
else
{
myStack.Push(d);
return false;
}
}
}
if(myStack.Count == 0)
{
return true;
}
else
{
return false;
}
}
最后一点代码,这些是正在检查的所有测试。 我目前正在为测试编号 9 / TestFLongMatch 苦苦挣扎。
public void TestFLongMatch()
{
Assert.That(ParenthesisMatcher.IsBalanced("(a{[]b({})}c)[]"), Is.True);
}
以下是包含所有测试的完整文件
/* ParenthesisMatcherTests.cs
* Author: Rod Howell
*/
using NUnit.Framework;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Ksu.Cis300.Parentheses;
namespace Ksu.Cis300.Parentheses.Tests
{
/// <summary>
/// A unit test class for the class library Ksu.Cis300.Parentheses.
/// </summary>
[TestFixture]
public class ParenthesisMatcherTests
{
/// <summary>
/// Checks the empty string, which is balanced.
/// </summary>
[Test, Timeout(1000)]
public void TestAEmptyString()
{
Assert.That(ParenthesisMatcher.IsBalanced(""), Is.True);
}
/// <summary>
/// Checks the string "abcdefg", which is balanced.
/// </summary>
[Test, Timeout(1000)]
public void TestBNoParentheses()
{
Assert.That(ParenthesisMatcher.IsBalanced("abcdefg"), Is.True);
}
/// <summary>
/// Checks the string "[", which is not balanced.
/// </summary>
[Test, Timeout(1000)]
public void TestCOpeningParenthesis()
{
Assert.That(ParenthesisMatcher.IsBalanced("["), Is.False);
}
/// <summary>
/// Checks the string ")", which is not balanced.
/// </summary>
[Test, Timeout(1000)]
public void TestDClosingParenthesis()
{
Assert.That(ParenthesisMatcher.IsBalanced(")"), Is.False);
}
/// <summary>
/// Tests the string "{{}", which is not balanced.
/// </summary>
[Test, Timeout(1000)]
public void TestEMissingClose()
{
Assert.That(ParenthesisMatcher.IsBalanced("{{}"), Is.False);
}
/// <summary>
/// Tests the string "[[]", which is not balanced.
/// </summary>
[Test, Timeout(1000)]
public void TestEExtraClose()
{
Assert.That(ParenthesisMatcher.IsBalanced("[]]"), Is.False);
}
/// <summary>
/// Tests the string "[}", which is not balanced.
/// </summary>
[Test, Timeout(1000)]
public void TestEMismatch()
{
Assert.That(ParenthesisMatcher.IsBalanced("[}"), Is.False);
}
/// <summary>
/// Tests the string "[}]", which is not balanced.
/// </summary>
[Test, Timeout(1000)]
public void TestEMismatch2()
{
Assert.That(ParenthesisMatcher.IsBalanced("[}]"), Is.False);
}
/// <summary>
/// Tests the string "(a{[]b({})}c)[]", which is balanced.
/// </summary>
[Test, Timeout(1000)]
public void TestFLongMatch()
{
Assert.That(ParenthesisMatcher.IsBalanced("(a{[]b({})}c)[]"), Is.True);
}
/// <summary>
/// Tests the string "(a{[]b({})}c)[](", whose last parenthesis is not matched.
/// </summary>
[Test, Timeout(1000)]
public void TestFLongMissingClose()
{
Assert.That(ParenthesisMatcher.IsBalanced("(a{[]b({})}c)[]("), Is.False);
}
/// <summary>
/// Tests the string "(a{[]b({})}c)[]())", whose last parenthesis is not matched.
/// </summary>
[Test, Timeout(1000)]
public void TestFLongExtraClose()
{
Assert.That(ParenthesisMatcher.IsBalanced("(a{[]b({})}c)[]())"), Is.False);
}
/// <summary>
/// Tests the string "(a{[]b({})}c}[]", whose first character is paired with the last '}', and
/// hence is mismatched.
/// </summary>
[Test, Timeout(1000)]
public void TestFLongMismatch()
{
Assert.That(ParenthesisMatcher.IsBalanced("(a{[]b({})}c}[]"), Is.False);
}
}
}
当我通过调试器运行特定测试时,代码将工作并运行字符串,直到它到达第一个右括号为止。 一旦结束括号起作用,并且开始和结束括号从测试中删除,程序停止返回false。 但是,它应该继续通过字符串并返回 True。 老实说,我迷失在这段代码中,因为其他与此非常相似的匹配字符串通过了,并且在第一个结束点后没有退出。
任何关于如何解决这个问题的建议将不胜感激。 如果需要其他任何帮助,请告诉我,我尝试包含尽可能多的信息。
从查看代码来看,我认为问题在于您的IsBalanced
方法在IsBalanced
右括号时立即返回false
。
在您的代码中,当遇到右括号时,有以下选项:
return false
return true
return false
要解决此问题,您可能需要使用Matches
方法来检查右括号是否与从堆栈中弹出的字符匹配:
public static bool IsBalanced(string input)
{
var stack = new Stack<char>();
foreach (var chr in input)
{
if (IsOpeningParenthesis(chr))
{
stack.Push(chr);
}
else if (IsClosingParenthesis(chr))
{
if (stack.Count == 0) return false;
if (!Matches(stack.Pop(), chr)) return false;
}
}
return stack.Count == 0;
}
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