HDU1195 BFS

题意：从一个4位数到另一个4位数 所需的步数

bfs

#include<stdio.h>
#include<string>
#include<stdlib.h>
#include<queue>
#include<algorithm>
#include<iostream>
#include<map>
using namespace std;
const int maxn = 10;
char a[maxn],b[maxn];
int vis[ 100000 ];
struct node{
    char nn[maxn];
    int t;
};

int solve( char a,char b,char c, char d ){
    return (a-'0')*1+(b-'0')*10+(c-'0')*100+(d-'0')*1000;
}

int bfs(){
    queue<node>q;
    while( !q.empty() )
        q.pop();
    node now,next;
    memset( vis,0,sizeof( vis ));
    strcpy( now.nn,a );//now.nn=a;
    vis[ solve(a[0],a[1],a[2],a[3]) ]=1;
    now.t=0;
    q.push( now );
    while( !q.empty() ){
        now=q.front(),q.pop();
        //printf("now:%s\n",now.nn);
        if( solve(now.nn[0],now.nn[1],now.nn[2],now.nn[3]) == solve( b[0],b[1],b[2],b[3] ) )
            return now.t;
        //next.nn=now.nn;
        next.t=now.t+1;
        for( int i=0;i<4;i++ ){
            strcpy( next.nn,now.nn );//.nn=now.nn;
            if( next.nn[i]=='9' ){
                next.nn[i]='1';
            }
            else{
                next.nn[i]=now.nn[i]+1;
            }
            if( vis[ solve(next.nn[0],next.nn[1],next.nn[2],next.nn[3]) ]==0/*mp[ next.nn ]==0*/ ){
                vis[ solve(next.nn[0],next.nn[1],next.nn[2],next.nn[3]) ]=1;
                q.push( next );
            }
        }//add 1
        for( int i=0;i<4;i++ ){
            strcpy( next.nn,now.nn );//next.nn=now.nn;
            if( next.nn[i]=='1' ){
                next.nn[i]='9';
            }
            else{
                next.nn[i]=now.nn[i]-1;
            }
            if( vis[ solve(next.nn[0],next.nn[1],next.nn[2],next.nn[3]) ]==0/*mp[ next.nn ]==0*/ ){
                vis[ solve(next.nn[0],next.nn[1],next.nn[2],next.nn[3]) ]=1;
                q.push( next );
            }
        }
        char tmp;
        for( int i=1;i<4;i++ ){
            strcpy( next.nn,now.nn );//next.nn=now.nn;
            tmp=now.nn[i];
            next.nn[i]=now.nn[i-1];
            next.nn[i-1]=tmp;
            if( vis[ solve(next.nn[0],next.nn[1],next.nn[2],next.nn[3]) ]==0/*mp[ next.nn ]==0*/ ){
                vis[ solve(next.nn[0],next.nn[1],next.nn[2],next.nn[3]) ]=1;
                q.push( next );
            }
        }
    }
    return -1;
}

int main(){
    int ca;
    scanf("%d",&ca);
    while( ca-- ){
        scanf("%s%s",a,b);
        int ans=bfs();
        printf("%d\n",ans);
    }
    return 0;
}