20. Valid Parentheses
原题链接:https://leetcode.com/problems/valid-parentheses/description/
这道题目是括号匹配问题,典型的栈的应用!使用栈可以很轻松的解决之:
import java.util.Stack;
/**
* Created by clearbug on 2018/2/26.
*/
public class Solution {
public static void main(String[] args) {
Solution s = new Solution();
System.out.println(s.isValid("()")); // true
System.out.println(s.isValid("()[]{}")); // true
System.out.println(s.isValid("(]")); // false
System.out.println(s.isValid("([)]")); // false
}
public boolean isValid(String s) {
Stack<Character> stack = new Stack<>();
char[] chars = s.toCharArray();
int len = chars.length;
if (len % 2 != 0) {
return false;
}
for (char c : chars) {
if (!stack.empty()) {
char stackTopEle = stack.peek();
switch (stackTopEle) {
case '(':
if (c == ')') {
stack.pop();
continue;
}
break;
case '[':
if (c == ']') {
stack.pop();
continue;
}
break;
case '{':
if (c == '}') {
stack.pop();
continue;
}
break;
}
}
stack.push(c);
}
if (stack.empty()) {
return true;
}
return false;
}
}