字符串の处理方式

#include<bits/stdc++.h>

using namespace std;

struct node{
    string p;
    int step;
};

int main(){
    int q;
    cin >> q;
    while(q --){
        string a,b;
        cin >> a >> b;
        queue<node> q;
        q.push({a,0});
        map<string,bool> vis = {};
        vis[a] = 1;
        while(!q.empty()){
            string s = q.front().p;
            int istep = q.front().step;
            q.pop();
            if(s == b){
                cout << istep << endl;
                break;
            }
            for(int i = 0;i < s.size() - 1;i ++){
                string np = s;
                swap(np[i],np[i + 1]);
                if(vis[np] == 0){
                    vis[np] = 1;
                    q.push({np,istep + 1});
                }
            }
            for(int i = 0;i < s.size();i ++){
                string np2 = s;
                string np3 = s;
                np2[i] --;
                np3[i] ++;
                if(np2[i] < '1'){
                    np2[i] = '9';
                }
                if(np3[i] > '9'){
                    np3[i] = '1';
                }
                if(vis[np2] == 0){
                    vis[np2] = 1;
                    q.push({np2,istep + 1});
                }
                if(vis[np3] == 0){
                    vis[np3] = 1;
                    q.push({np3,istep + 1});
                }
            }
        }
    }
    return 0;
}