HUST 1605 Gene recombination

简单广搜。4进制对应的10进制数来表示这些状态，总共只有（4^12）种状态。

#include<cstdio>
#include<cstring>
#include<cmath>
#include<map>
#include<queue>
#include<algorithm>
using namespace std;

const int maxn = ;
bool m[];
struct P
{
    int state;
    int tot;
};
queue<P>Q;
char s1[maxn], s2[maxn];
int tmp1[maxn], r1, tmp2[maxn], r2;
int A, B;
int n;
int b[maxn];

int f(char sign)
{
    if (sign == 'A') return ;
    if (sign == 'T') return ;
    if (sign == 'G') return ;
    if (sign == 'C') return ;
}

void init()
{
    while (!Q.empty()) Q.pop();
    memset(m, , sizeof m); A = B = ;
    for (int i = ; s1[i]; i++) A = A + f(s1[i])*b[i];
    for (int i = ; s2[i]; i++) B = B + f(s2[i])*b[i];
}

void BFS()
{
    P now; now.state = A; now.tot = ; m[A] = ; Q.push(now);
    while (!Q.empty())
    {
        P head = Q.front(); Q.pop();
        if (head.state == B)
        {
            printf("%d\n", head.tot);
            break;
        }

        memset(tmp1, , sizeof tmp1);
        memset(tmp2, , sizeof tmp2);

        r2 = r1 = ; int w = head.state;
        while (w) tmp2[r2++] = tmp1[r1++] = w % , w = w / ;

        swap(tmp1[], tmp1[]);
        int new_state = ;
        for (int i = ; i < n; i++) new_state = new_state + tmp1[i] * b[i];

        if (m[new_state] == )
        {
            m[new_state] = ;
            P d; d.state = new_state; d.tot = head.tot + ;
            Q.push(d);
        }

        new_state = ;
        tmp2[n] = tmp2[];
        for (int i = ; i <= n; i++) new_state = new_state + tmp2[i] * b[i - ];

        if (m[new_state] == )
        {
            m[new_state] = ;
            P d; d.state = new_state; d.tot = head.tot + ;
            Q.push(d);
        }
    }
}

int main()
{
    b[] = ; for (int i = ; i <= ; i++) b[i] =  * b[i - ];

    while (~scanf("%d", &n))
    {
        scanf("%s%s", s1, s2);
        init();
        BFS();
    }
    return ;
}