/*ID: qq104801LANG: C++TASK: msquare*/#include <iostream>#include <fstream>#include <queue>#include <set>#include <string>#include <algorithm>using namespace std;struct node{    int d;    string st,str;    node(string _st,string _str,int _d)    {st=_st;str=_str;d=_d;}};string end="";set<string> ss;queue<node> q;node bfs(){    string x="12345678";    if(end==x)return node("","",0);    q.push(node(x,"",0));    ss.insert(x);    while(!q.empty())    {        node curr=q.front();        q.pop();        string c=curr.st;        string a(c.rbegin(),c.rend());        if(a==end) return node(a,curr.str+"A",curr.d+1);        if(!ss.count(a))        {            ss.insert(a);            q.push(node(a,curr.str+"A",curr.d+1));        }        string b(c[3]+c.substr(0,3)+c.substr(5)+c[4]);        if(b==end)return node(b,curr.str+"B",curr.d+1);        if(!ss.count(b))        {            ss.insert(b);            q.push(node(b,curr.str+"B",curr.d+1));        }        swap(c[1],c[2]);swap(c[1],c[5]);swap(c[1],c[6]);        if(c==end)return node(c,curr.str+"C",curr.d+1);        if(!ss.count(c))        {            ss.insert(c);            q.push(node(c,curr.str+"C",curr.d+1));        }    }}void test(){        freopen("msquare.in","r",stdin);    freopen("msquare.out","w",stdout);    char c;    for(int i=0;i<8;i++){        cin>>c;        end+=c;    }    node n=bfs();    cout<<n.d<<endl<<n.str<<endl;}int main () {            test();            return 0;}

USACO TrainingGrader Results     8 users onlineCHN/4 KGZ/1 MYS/1 SGP/1 TTO/1USER: cn tom [qq104801]TASK: msquareLANG: C++Compiling...Compile: OKExecuting...   Test 1: TEST OK [0.019 secs, 3524 KB]   Test 2: TEST OK [0.003 secs, 3524 KB]   Test 3: TEST OK [0.016 secs, 3524 KB]   Test 4: TEST OK [0.005 secs, 3524 KB]   Test 5: TEST OK [0.046 secs, 4052 KB]   Test 6: TEST OK [0.092 secs, 4712 KB]   Test 7: TEST OK [0.159 secs, 5636 KB]   Test 8: TEST OK [0.270 secs, 6032 KB]All tests OK.YOUR PROGRAM (‘msquare‘) WORKED FIRST TIME! That‘s fantastic -- and a rare thing. Please accept these special automated congratulations.Here are the test data inputs:------- test 1 ----2 6 8 4 5 7 3 1------- test 2 ----1 2 3 4 5 6 7 8------- test 3 ----6 7 4 1 8 5 2 3------- test 4 ----5 1 2 4 3 7 8 6------- test 5 ----6 1 5 4 3 2 7 8------- test 6 ----4 1 2 3 5 8 7 6------- test 7 ----3 4 2 1 5 6 7 8------- test 8 ----4 3 1 2 5 6 7 8Keep up the good work!Thanks for your submission!