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validParentheses.java
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55 lines (28 loc) · 1.39 KB
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// 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.
public class Solution {
public boolean isValid(String s) {
if(s.length() % 2 == 1) {
return false;
}
Stack<Character> stack = new Stack<Character>();
for(int i = 0; i < s.length(); i++) {
if(s.charAt(i) == '(' || s.charAt(i) == '[' || s.charAt(i) == '{') {
stack.push(s.charAt(i));
}
else if(s.charAt(i) == ')' && !stack.isEmpty() && stack.peek() == ')') {
stack.pop();
}
else if(s.charAt(i) == ']' && !stack.isEmpty() && stack.peek() == ']') {
stack.pop();
}
else if(s.charAt(i) == '}' && !stack.isEmpty() && stack.peek() == '}') {
stack.pop();
}
else {
return false;
}
}
return stack.isEmpty();
}
}