如何检查字符串是否平衡? [英] How to check if a String is balanced?

问题描述

我想测试输入String是否平衡.如果有匹配的左，右括号，括号或花括号，则会保持平衡.

I want to test if an input String is balanced. It would be balanced if there is a matching opening and closing parenthesis, bracket or brace.

example:
{} balanced
() balanced
[] balanced
If S is balanced so is (S)
If S and T are balanced so is ST


public static boolean isBalanced(String in)
{
    Stack st = new Stack();

    for(char chr : in.toCharArray())
    {
        if(chr == '{')
            st.push(chr);

    }

    return false;
}

我在选择做什么时遇到了问题.我是否应该将每个左括号或右括号，方括号或大括号放在堆栈中，然后弹出它们?如果我将它们弹出，那对我有什么帮助?

I'm having problems choosing what to do. Should I put every opening or closing parenthesis, bracket, or brace in a stack then pop them out? If I pop them out, how does that really help me?

推荐答案

1)对于每个左括号:{ [ (将其推入堆栈.

1) For every opening bracket: { [ ( push it to the stack.

2)对于每个右括号:} ] )从堆栈中弹出，并检查括号的类型是否匹配.如果没有返回false;

2) For every closing bracket: } ] ) pop from the stack and check whether the type of bracket matches. If not return false;

即，字符串中的当前符号为}，如果从堆栈中弹出的是{中的其他符号，则立即返回false.

i.e. current symbol in String is } and if poped from stack is anything else from { then return false immediately.

3)如果行和堆栈的末尾不为空，则返回false，否则返回true.

3) If end of line and stack is not empty, return false, otherwise true.

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