暴力做的，后来写完的，一开始只能过56，后来改了下，也不知道能不能过全部 public class Lianjia3 { private static boolean isTrue(int[] verify,int[] data, int n){ for (int i=0;i<n;++i){ if (verify[i]!=data[i]){ return false; } } return true; } private static void swap(int i,int j,int[] data){ int t=data[i]; data[i]=data[j]; data[j]=t; } private static int ans=Integer.MAX_VALUE; public static void solve(int index,int[] verify,int[] data,int n,int cur){ if (isTrue(verify, data, n)){ ans=Math.min(ans, cur); return; } if (verify[index]==data[index]){ solve(index+1, verify, data, n, cur); return; } int id=-1; for (int j=index+1;j<n;++j){ if(data[j]==verify[index] && verify[j]==data[index]){ id=j; break; } } if(id!=-1){ swap(index, id, data); solve(index+1, verify, data, n, cur+1); } if (id==-1){ for (int j=index+1;j<n;++j){ if(data[j]==verify[index] && verify[j]!=data[j]){ id=j; swap(index, j, data); solve(index+1, verify, data, n, cur+1); swap(index, j, data); } } } } public static void main(String[] args) { // TODO Auto-generated method stub Scanner in=new Scanner(System.in); int n=in.nextInt(); int[] data=new int[n]; int oneCount=0; int twoCount=0; int threeCount=0; for (int i=0;i<n;++i){ data[i]=in.nextInt(); if (data[i]==1){ oneCount++; }else if (data[i]==2){ twoCount++; }else{ threeCount++; } } int[] verify=new int[n]; int i=0; for (int j=0;j<oneCount;++j){ verify[i++]=1; } for (int j=0;j<twoCount;++j){ verify[i++]=2; } for (int j=0;j<threeCount;++j){ verify[i++]=3; } solve(0,verify, data, n, 0); System.out.println(ans); in.close(); } }