hdu 1195 Open the Lock 双广

//题目大意：求解开4位密码锁的最少步数.

//    <变化一次：加1；减1；邻位交换>

思路：简单bfs能过，时间很高，双bfs好点。

 

简单bfs

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <iostream>
#include <queue>
#include <algorithm>
using namespace std;
struct nd
{
    int num,st;
};
int hash[10000];
int s,t;
int tmp[100],k;
void swap(char& a,char& b){ char c = a; a = b; b = c; }
void fun(int x)
{
    char str[5],i;
    sprintf(str,"%d",x);
    k = 0;
    for(i = 0; i < 4; ++ i)
    {
        if(str[i]=='9'){
            str[i]='1';
            sscanf(str,"%d",tmp+k); k++;
            str[i]='8';
            sscanf(str,"%d",tmp+k); k++;
            str[i]='9';
        }else if(str[i]=='1'){
            str[i]='9';
            sscanf(str,"%d",tmp+k); k++;
            str[i]='2';
            sscanf(str,"%d",tmp+k); k++;
            str[i]='1';
        }else{
            str[i]++;
            sscanf(str,"%d",tmp+k); k++;
            str[i] -= 2;
            sscanf(str,"%d",tmp+k); k++;
            str[i]++;
        }
    }
    swap(str[0],str[1]);
    sscanf(str,"%d",tmp+k); k++;
    swap(str[0],str[1]);
    swap(str[1],str[2]);
    sscanf(str,"%d",tmp+k); k++;
    swap(str[1],str[2]);
    swap(str[2],str[3]);
    sscanf(str,"%d",tmp+k); k++;
}
int bfs()
{
    int i,j;
    if(s==t)return 0;
    memset(hash,0,sizeof(hash));
    hash[s] = 1;
    queue<nd>que;
    nd ps;
    ps.num = s;
    ps.st = 0;
    que.push(ps);
    while(!que.empty())
    {
        nd qs = que.front(); que.pop();
        qs.st++;
        fun(qs.num);
        for(i = 0; i < k; ++ i)if(!hash[tmp[i]])
        {
            if(tmp[i]==t)return qs.st;
            qs.num = tmp[i];
            hash[tmp[i]] = 1;
            que.push(qs);
        }
    }
    return 0;
}
int main()
{
    int i,j,ans,cas;
    scanf("%d",&cas);
    while(cas--)
    {
        scanf("%d %d",&s,&t);
        ans = bfs();
        printf("%d\n",ans);
    }return 0;
}

双广：

#include<set>
#include<map>
#include<stack>
#include<queue>
#include<cmath>
#include<bitset>
#include<string>
#include<climits>
#include<cstdio>
#include<vector>
#include<utility>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<algorithm>
#define IN puts("in")
#define OUT puts("out")
#define FR(x) freopen(x,"r",stdin)
#define FW(x) freopen(x,"w",stdout)
#define MSET(x,y) memset(x,y,sizeof(x))
#define ST system("pause")

using namespace std;
int hash[10000],hash2[10000];
int s,t;
int tmp[100],k;
void swap(char& a,char& b){ char c = a; a = b; b = c; }
void fun(int x)
{
    char str[5],i;
    sprintf(str,"%d",x);
    k = 0;
    for(i = 0; i < 4; ++ i)
    {
        if(str[i]=='9'){
            str[i]='1';
            sscanf(str,"%d",tmp+k); k++;
            str[i]='8';
            sscanf(str,"%d",tmp+k); k++;
            str[i]='9';
        }else if(str[i]=='1'){
            str[i]='9';
            sscanf(str,"%d",tmp+k); k++;
            str[i]='2';
            sscanf(str,"%d",tmp+k); k++;
            str[i]='1';
        }else{
            str[i]++;
            sscanf(str,"%d",tmp+k); k++;
            str[i] -= 2;
            sscanf(str,"%d",tmp+k); k++;
            str[i]++;
        }
    }
    sprintf(str,"%d",x);
    for(i = 0; i < 3; ++ i){
        swap(str[i],str[i+1]);
        sscanf(str,"%d",tmp+k); k++;
        swap(str[i],str[i+1]);
    }
}
int bfs()
{
    int i,j;
    if(s==t)return 0;
    memset(hash,-1,sizeof(hash));
    memset(hash2,-1,sizeof(hash2));
    hash[s] = 0;
    hash2[t] = 0;
    queue<int>que;
    queue<int>que2;
    que.push(s);
    que2.push(t);
    int pre1 = 0;
    int pre2 = 0;
    while(1)
    {
        while(!que.empty()){
            int qs = que.front();
            if(hash[qs]!=pre1){ pre1 = hash[qs]; break;}
            que.pop();
            fun(qs);
            for(i = 0; i < k; ++ i)if(hash[tmp[i]]<0)
            {
                hash[tmp[i]] = hash[qs] + 1;
                if(hash2[tmp[i]]>=0)return hash[tmp[i]]+hash2[tmp[i]];
                que.push(tmp[i]);
            }else if(hash2[tmp[i]]>=0)return hash[tmp[i]]+hash2[tmp[i]];
        }
        while(!que2.empty()){
            int qs = que2.front();
            if(pre2 != hash2[qs]){ pre2 = hash2[qs]; break;}
            que2.pop();
            fun(qs);
            for(i = 0; i < k; ++ i)if(hash2[tmp[i]]<0)
            {
                hash2[tmp[i]] = hash2[qs] + 1;
                if(hash[tmp[i]]>=0)return hash2[tmp[i]]+hash[tmp[i]];
                que2.push(tmp[i]);
            }else if(hash[tmp[i]]>=0)return hash2[tmp[i]]+hash[tmp[i]];
        }
    }
    return 0;
}

int main()
{
    int i,j,ans,cas;
    scanf("%d",&cas);
    while(cas--)
    {
        scanf("%d %d",&s,&t);
        ans = bfs();
        printf("%d\n",ans);
    }return 0;
}