hust 1605 bfs

思路：直接用优先队列优化bfs。

#include<map>

#include<queue>

#include<vector>

#include<cmath>

#include<string>

#include<cstdio>

#include<cstring>

#include<iostream>

#include<algorithm>

#define Maxn 100010

#define inf 1<<30

using namespace std;

map<int,int> g;

int ans,n,ha[255],Exp[15];

char s[13];

int tar;

struct QT{

    int val,st;

    int operator <(const QT &temp) const{

        return st>temp.st;

    }

};

priority_queue<QT> q;

int bfs(int temp)

{

    int i,j,str;

    while(!q.empty()) q.pop();

    QT tt,p;

    tt.val=temp,tt.st=0;

    q.push(tt);

    while(!q.empty()){

        p=q.top();

        q.pop();

        str=p.val;

        if(str==tar) return p.st;

        int a,b;

        a=str/Exp[n-1];

        b=str%Exp[n-1]/Exp[n-2];

        temp=b*Exp[n-1]+a*Exp[n-2]+str%Exp[n-2];

        if(!g[temp]){

            tt.val=temp,tt.st=p.st+1;

            q.push(tt);

            g[temp]=1;

        }

        temp=str%Exp[n-1]*5+str/Exp[n-1];

        if(!g[temp]){

            tt.val=temp,tt.st=p.st+1;

            q.push(tt);

            g[temp]=1;

        }

    }

}

int main()

{

    char str[13];

    int i,j;

    ha['A']=1;

    ha['G']=2;

    ha['C']=3;

    ha['T']=4;

    Exp[0]=1;

    for(int i=1;i<15;i++)

        Exp[i]=Exp[i-1]*5;

    while(scanf("%d",&n)!=EOF){

        ans=inf;

        g.clear();

        scanf("%s%s",str,s);

        tar=0;

        int temp=0;

        for(i=0;i<n;i++){

            tar=tar*5+ha[s[i]];

            temp=temp*5+ha[str[i]];

        }

        printf("%d\n",bfs(temp));

    }

    return 0;

}