InputYour program will be tested on one or more data sets. Each data set is described on a single line. The line is a non-empty string of opening and closing braces and nothing else. No string has more than 2000 braces. All sequences are of even length.
The last line of the input is made of one or more ’-’ (minus signs.)
OutputFor each test case, print the following line:
k. N
Where k is the test case number (starting at one,) and N is the minimum number of operations needed to convert the given string into a balanced one.
Note: There is a blank space before N.
Sample Inputjava
}{ {}{}{} {{{} ---
Sample Outputthis
1. 2 2. 0 3. 1
題意:問須要改變幾個括號才能使字符串是stable
思路:對左括號計數;遇到右括號:若是有左括號則配對一個,左括號數減一;若是沒有左括號,那麼右括號必定是須要修改的
代碼:
import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner scan=new Scanner(System.in); int k=1; while(scan.hasNext()){ String s=scan.next(); if(s.charAt(0)=='-') break; int len=s.length(); int cnt=0,c=0;//cnt須要改變的數量;c爲{的數量 for(int i=0;i<len;i++){ if(s.charAt(i)=='{'){ c++; } else{ if(c>0) c--; else{ c++; cnt++; } } } cnt+=c/2; System.out.println((k++)+". "+cnt); } } }