7/23·afternoon

问题 A: 魔法鲜花  http://www.jzoj.cn/problem.php?cid=5707&pid=0

#include<bits/stdc++.h>
using namespace std;
int s,t;
int vis[100007];
struct node{
    int num;
    string path;
};
string ABC="ABC";
int main(){
    memset(vis,-1,sizeof(vis));
    cin>>s>>t;
    if(s==t){
        cout<<0;
        return 0;
    }
    queue<node> q;
    while(!q.empty())q.pop();
    q.push({s,""});
    vis[s]=0;
    while(!q.empty()){
        int frontn=q.front().num;
        string frontp=q.front().path;
        q.pop();
        for(int i=0;i<3;i++){
            int x=frontn;
            if(i==0)x+=1;
            if(i==1&&x>10)x-=10;
            if(i==2)x*=2;
            if(x>0&&x<=100000&&vis[x]==-1){
                q.push({x,frontp+ABC[i]});
                vis[x]=vis[frontn]+1;
                if(x==t){
                    cout<<vis[x]<<endl;
                    cout<<frontp+ABC[i];
                    return 0;
                }
            }
        }
    }
    return 0;
}
/*换了一种路径记录方式*/

问题 E: 最少点路径  http://www.jzoj.cn/problem.php?cid=5707&pid=4

#include<bits/stdc++.h>
using namespace std;
int N,s,t;
int a[13][13];
bool vis[13];
struct node{
    int w;
    string path;
};
queue<node> q;
int main(){
    cin>>N;
    for(int i=1;i<=N;i++){
        for(int j=1;j<=N;j++){
            cin>>a[i][j];
        }
    }
    cin>>s>>t;
    
    while(!q.empty())q.pop();
    string st="";st+=char(s+48);
    q.push({s,st});
    vis[s]=1;
    while(!q.empty()){
        int x=q.front().w;
        string pa=q.front().path;
        q.pop();
        //cout<<x<<endl;
        for(int i=1;i<=N;i++){
            string p=pa+'-'+char(i+48);
            if(a[x][i]==1&&!vis[i]){
                q.push({i,p});
                vis[i]=1;
                if(i==t){
                    cout<<p<<endl;
                    return 0;
                }
            }
            
        }
    }
    return 0;
}
 

问题 F: 八数码问题  http://www.jzoj.cn/problem.php?cid=5707&pid=5

#include<bits/stdc++.h>
using namespace std;
/*
0 1 2
3 4 5
6 7 8
*/
string start,finish;
struct node{
    string a;
    int b,k;
};
int mov[4]={-3,3,1,-1};
set<string> vis;
string change(string str,int cz,int kk){
    int ch=kk+mov[cz];
    if(ch<0||ch>8||cz==3&&kk==3||cz==3&&kk==6||cz==2&&kk==2||cz==2&&kk==5)return "NO";
    else{
        string strr=str;
        swap(strr[kk],strr[ch]);
        return strr;
    }
}
int main(){
    cin>>start;
    cin>>finish;
    if(start==finish){//特判!!!
        cout<<0;
        return 0;
    }
    queue<node> q;
    while(!q.empty())q.pop();
    int z=0;while(start[z]!='0')z++;
    q.push({start,0,z});
    vis.insert(start);
    while(!q.empty()){
        string fronta=q.front().a;
        int frontb=q.front().b;
        int frontk=q.front().k;
        q.pop();
        for(int i=0;i<4;i++){
            string str=change(fronta,i,frontk);
            if(str!="NO"&&vis.count(str)==0){
                q.push({str,frontb+1,frontk+mov[i]});
                vis.insert(str);
                if(str==finish){
                    cout<<frontb+1;
                    return 0;
                } 
            }
        }
    }
    cout<<"impossible";
    return 0;
}