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package stack.issue;

import java.util.Stack;

/**

* leetcode-20-有效的括号

* <p>

* 给定一个只包括 '('，')'，'{'，'}'，'['，']' 的字符串，判断字符串是否有效。

* <p>

* 有效字符串需满足：

* <p>

* 左括号必须用相同类型的右括号闭合。

* 左括号必须以正确的顺序闭合。

* 示例 1:

* <p>

* 输入: "()"

* 输出: true

*/

public class BracketIssueSolution {

public static boolean isValid(String str) {

Stack<Character> stack = new Stack<>();

for (int i = 0; i < str.length(); i++) {

char c = str.charAt(i);

if (c == '(' || c == '{' || c == '[') {

stack.push(c);

} else if (c == ')' || c == ']' || c == '}'){

if (stack.isEmpty()) {

return false;

}

char topChar = stack.pop();

if (c == ')' && topChar != '(') {

return false;

}

if (c == '}' && topChar != '{') {

return false;

}

if (c == ']' && topChar != '[') {

return false;

}

}

}

return stack.isEmpty();

}

public static void main(String[] args) {

boolean valid = isValid("{x+b+b*{(1+2)}}");

System.out.println(valid);

}

}