-
Notifications
You must be signed in to change notification settings - Fork 0
/
Solution.java
75 lines (70 loc) · 1.89 KB
/
Solution.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
package validparentheses;
import java.util.Stack;
/**
* Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
*
* An input string is valid if:
*
* Open brackets must be closed by the same type of brackets.
* Open brackets must be closed in the correct order.
* Note that an empty string is also considered valid.
*
* Example 1:
*
* Input: "()"
* Output: true
* Example 2:
*
* Input: "()[]{}"
* Output: true
* Example 3:
*
* Input: "(]"
* Output: false
* Example 4:
*
* Input: "([)]"
* Output: false
* Example 5:
*
* Input: "{[]}"
* Output: true
*/
public class Solution {
public boolean isValid(String s) {
Stack<Character> parens = new Stack<>();
if(s.length() == 0) return true;
boolean isValid = false;
for(char c: s.toCharArray()) {
switch(c) {
case '(':
case '[':
case '{':
parens.push(c);
break;
case ')':
case ']':
case '}':
if(parens.isEmpty()) return false;
char curr = parens.pop();
if((c == ')' && curr != '(')
|| (c == ']' && curr != '[')
|| (c == '}' && curr != '{')
) {
return false;
}
else {
isValid = true;
}
}
}
// if stack is still not empty - then there are mismatched parentheses still present - invalid expression
return parens.isEmpty() && isValid;
}
}
/*
Success
Details
Runtime: 1 ms, faster than 98.68% of Java online submissions for Valid Parentheses.
Memory Usage: 37.9 MB, less than 5.06% of Java online submissions for Valid Parentheses.
*/