Given a string containing just the characters ‘(‘, ‘)‘, ‘{‘, ‘}‘, ‘[‘ and ‘]‘, determine if the input string is valid.
An input string is valid if:
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
1 class Solution { 2 public char map(char c) { 3 if (c == ‘)‘) return ‘(‘; 4 if (c == ‘]‘) return ‘[‘; 5 if (c == ‘}‘) return ‘{‘; 6 return ‘ ‘; 7 } 8 public boolean isValid(String s) { 9 int n = s.length(); 10 Map<String, String> map = new HashMap<>(); 11 12 if (n == 0) return true; 13 char []stack = new char[n]; 14 int k = 0; 15 for (int i = 0; i < n; ++i) { 16 char c = s.charAt(i); 17 if (c == ‘(‘ || c == ‘[‘ || c == ‘{‘) { 18 stack[k++] = c; 19 } else { 20 if (k == 0 || stack[--k] != map(c)) { 21 return false; 22 } 23 } 24 } 25 if (k== 0) 26 return true; 27 else 28 return false; 29 } 30 }
原文：https://www.cnblogs.com/hyxsolitude/p/12304889.html