找到第一个外括号 [英] Find the first outer brackets

问题描述

我需要找出第一个最外面的（非嵌套的）括号索引。

I need to find out the first outermost(not nested) brackets indexes.

例如

[]                         output: 0, 1
1[2]                       output: 1, 3
3[a2[c]]2[abc]3[cd]        output: 1, 7

我可以通过很多条件找到它，当前代码为：

I can find it by lots of conditions, current code:

public static void main(String[] args) {
    String input = "3[a2[c]]2[abc]3[cd]ef";
    int first = 0;
    int second = 0;

    int count = 0;
    boolean found = false;
    for (int index = 0; index < input.length(); index++) {
        if (input.charAt(index) == '[') {
            count++;
            if (found == false) {
                found = true;
                first = index;
            }
        } else if (input.charAt(index) == ']') {
            count--;
            if (found && count == 0) {
               second = index;
               break;
            }
        }
    }

    System.out.println(first);
    System.out.println(second);
}

是否还有更多的干净

Is there more clean way to do it?

推荐答案

使用 Stack 可能更多优雅：

String input = "3[a2[c]]2[abc]3[cd]ef";
Stack<Integer> stack = new Stack<> ();
int first = -1;
int second = -1;

for (int index = 0; index < input.length(); index++) {
    if (input.charAt(index) == '[') {
        stack.push(index);
    } else if (input.charAt(index) == ']' && !stack.isEmpty ()) {
        first = stack.pop ();
        if (stack.isEmpty ()) {
            second = index;
            break;
        }
    }
}

if (first >= 0 && second >= 0) {
    System.out.println(first);
    System.out.println(second);
} else {
  System.out.println ("not found");
}

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