• 思路
    • 交换结果只有两种，鸡左或鸡右，两种同时进行，取其中最小值输出即可
  • 代码
    import java.io.BufferedReader;
    import java.io.IOException;
    import java.io.InputStreamReader;
    public class Main {
    public static void main(String[] args) throws IOException {
      BufferedReader b = new BufferedReader(new InputStreamReader(System.in));
  char[] all = b.readLine().toCharArray();
  int numC=0,numD=0,countC=0,countD=0;
  for(int i=0;i<all.length;i++)
  {
      if(all[i]=='C')
      {
          numC++;
          countD+=numD;
      }
      if(all[i]=='D')
      {
          numD++;
          countC+=numC;
      }
  }
  System.out.print(countC>countD?countD:countC);
    }
    }