CodeForMaster/src/com/leetcode/ValidParentheses.java at master · lujiamin/CodeForMaster · GitHub

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
package com.leetcode;

import java.util.Stack;

/**
 * Created by jamylu on 2018/1/2.
 * leetcode020
 * 括号匹配
 */
public class ValidParentheses {

    public static void main(String args[]) {
        String s = "()[]{[()]}";
        System.out.println(isValid(s));
    }

    public static boolean isValid(String s) {
        Stack<Character> st = new Stack<>();
        for (int i = 0; i < s.length(); i++) {
            if (s.charAt(i) == '(' || s.charAt(i) == '[' || s.charAt(i) == '{') {
                st.push(s.charAt(i));
            } else if (s.charAt(i) == ')') {
                if (!st.isEmpty() && st.peek() == '(')
                    st.pop();
                else
                    return false;
            } else if (s.charAt(i) == ']') {
                if (!st.isEmpty() && st.peek() == '[')
                    st.pop();
                else
                    return false;
            } else if (s.charAt(i) == '}') {
                if (!st.isEmpty() && st.peek() == '{')
                    st.pop();
                else
                    return false;
            }
        }
        if (st.isEmpty()) {
            return true;
        } else {
            return false;
        }
    }
}