前段时间面试华为时，考官问了一道小算法题。
微信图片_20200423223042.jpg
今天在看数据结构这本书时，想起了这道算法题。
其实就是使用栈这种数据结构判断一个中缀表达式中的分隔符，在这里做一个记录。
import java.util.Stack;
public class BalanceChecker {
public boolean checkBlance(String expression) {
boolean isBalanced = true;
int characterCount = expression.length();
Stack<Character> openDelimiterStack = new Stack<>();
int index = 0;
char nextCharacter = ' ';
while (isBalanced && index < characterCount) {
nextCharacter = expression.charAt(index);
if (nextCharacter == '(' || nextCharacter == '[' || nextCharacter == '{') {
openDelimiterStack.push(nextCharacter);
} else {
if (openDelimiterStack.empty()) {
isBalanced = false;
} else {
Character openDelimiter = openDelimiterStack.pop();
isBalanced = isPaired(openDelimiter, nextCharacter);
}
}
index++;
}
if (!openDelimiterStack.isEmpty())
isBalanced = false;
return isBalanced;
}
private boolean isPaired(Character open, Character close) {
return (open == '(' && close == ')') ||
(open == '[' && close == ']') ||
(open == '{' && close == '}');
}
}
