import java.util.ArrayList;
import java.util.Stack;
/**
<p>给定一个只包括 <code>'('</code>，<code>')'</code>，<code>'{'</code>，<code>'}'</code>，<code>'['</code>，<code>']'</code> 的字符串 <code>s</code> ，判断字符串是否有效。</p>
<p>有效字符串需满足：</p>
<ol>
<li>左括号必须用相同类型的右括号闭合。</li>
<li>左括号必须以正确的顺序闭合。</li>
</ol>
<p> </p>
<p><strong>示例 1：</strong></p>
<pre>
<strong>输入：</strong>s = "()"
<strong>输出：</strong>true
</pre>
<p><strong>示例 2：</strong></p>
<pre>
<strong>输入：</strong>s = "()[]{}"
<strong>输出：</strong>true
</pre>
<p><strong>示例 3：</strong></p>
<pre>
<strong>输入：</strong>s = "(]"
<strong>输出：</strong>false
</pre>
<p><strong>示例 4：</strong></p>
<pre>
<strong>输入：</strong>s = "([)]"
<strong>输出：</strong>false
</pre>
<p><strong>示例 5：</strong></p>
<pre>
<strong>输入：</strong>s = "{[]}"
<strong>输出：</strong>true</pre>
<p> </p>
<p><strong>提示：</strong></p>
<ul>
<li><code>1 <= s.length <= 10<sup>4</sup></code></li>
<li><code>s</code> 仅由括号 <code>'()[]{}'</code> 组成</li>
</ul>
<div><div>Related Topics</div><div><li>栈</li><li>字符串</li></div></div><br><div><li>???? 3187</li><li>???? 0</li></div>
*/
//leetcode submit region begin(Prohibit modification and deletion)
class Solution {
public boolean isValid(String s) {
Stack stack = new Stack<>();
for (int i = 0; i < s.length(); i++) {
char c= s.charAt(i);
if (c == '(' || c == '{' || c == '['){
stack.push(c);
}else{
if(stack.isEmpty()){
return false ;
}
char c1 = (char) stack.pop();
if ( c == '}' && c1 == '{' ) {
continue;
}
if ( c == ')' && c1 == '(' ) {
continue;
}
if ( c == ']' && c1 == '[' ) {
continue;
}
return false;
}
}
return stack.isEmpty();
}
}
//leetcode submit region end(Prohibit modification and deletion)
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