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  • Valid Parentheses

    Valid Parentheses

    问题:

    Given a string containing just the characters '('')''{''}''[' and ']', determine if the input string is valid.

    The brackets must close in the correct order, "()" and "()[]{}" are all valid but "(]" and "([)]" are not.

    思路:

      经典栈的应用

    我的代码:

    public class Solution {
        public boolean isValid(String s) {
            if(s == null || s.length() == 0) return true;
            Stack<Character> stack = new Stack<Character>();
            for(int i = 0; i < s.length(); i++)
            {
                char c = s.charAt(i);
                if(isRight(c))
                {
                    if(stack.isEmpty()) return false;
                    char left = stack.pop();
                    if(!isMatch(left,c)) return false;
                }
                else
                {
                    stack.push(c);
                }
            }
            return stack.isEmpty();
        }
        public boolean isMatch(char left, char right)
        {
            if((left=='('&&right==')')||(left=='['&&right==']')||(left=='{'&&right=='}'))   return true;
            return false;
        }
        public boolean isRight(char c)
        {
            if(c == ')' || c == ']' || c == '}')    return true;
            return false;
        }
    }
    View Code
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  • 原文地址:https://www.cnblogs.com/sunshisonghit/p/4336041.html
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