求最深字符串Output the most inner string

1. Output the most inner string:  "ab(cd(e)fg)" => "e", "Hello World!" =>"Hello World!" "ab{cd[ef]} gh(hello{hi})" =>"ef", "hi"

先用https://www.geeksforgeeks.org/find-maximum-depth-nested-parenthesis-string/

 

// Traverse the input string  
        for (int i = 0; i < n; i++) { 
            if (S.charAt(i) == '(') { 
                current_max++; 
  
                // update max if required  
                if (current_max > max) { 
                    max = current_max; 
                } 
            } else if (S.charAt(i) == ')') { 
                if (current_max > 0) { 
                    current_max--; 
                } else { 
                    return -1; 
                } 
            } 
        } 

 

max和current_max求出最大深度。然后再来一次，最大深度的时候append

 

或者用：https://stackoverflow.com/questions/12595019/how-to-get-a-string-between-two-characters

一个不需要您执行indexOf的问题的非常有用的解决方案是使用Apache Commons库。

 StringUtils.substringBetween(s, "(", ")");