solution

有一个测试点没有空格，要特别处理，否则会有一个测试点运行错误！
还有输入数据的规模在变，小心顺手敲错了边界条件

#include<iostream>
#include<string>
#include<queue>
#include<map>
#include<algorithm>
using namespace std;
string start, t;
map<string, int> mp;
int ax, ay, x, y, d, k;
int X[4] = {-1, 1, 0, 0};
int Y[4] = {0, 0, -1, 1};

int bfs(string s){
    queue<string> q;
    q.push(s);
    while(!q.empty()){
        t = q.front();
        q.pop();
        if(t.find('A') == ay && t.find('B') == ax) return mp[t];
        k = t.find(' ');
        for(int i = 0; i < 4; i++){
            x = k / 3 + X[i];
            y = k % 3 + Y[i];
            if(x < 0 || x >= 2 || y < 0 || y >= 3) continue;
            d = mp[t];
            swap(t[k], t[3 * x + y]);
            if(!mp.count(t)){
                mp[t] = d + 1;
                q.push(t);
            }
            swap(t[k], t[3 * x + y]);
        }
    }
}

int main(){
    getline(cin, start);
    getline(cin, t);
    start = start + t;
    ax = start.find('A');
    ay = start.find('B');
    if(start.find(' ') == start.npos) cout << 10;
    else cout << bfs(start);
    return 0;
}