BZOJ1054(搜索)

        大力搜，状态用一个16位的数字表示。

       

#include <bits/stdc++.h>

using namespace std;

#define rep(i,a,b)              for(int i(a); i <= (b); ++i)

const int A     =    30          +       1;

struct node{int x, y; } op[A];
struct Node{int num, step;} now, np;

char st[A][A];
int f[A][A];
int h[1 << 18];
int x, y, nx, ny, s, t, cnt = 0;

queue <Node> Q;

int main(){

    rep(i, 1, 8) scanf("%s", st[i] + 1);
    cnt = 0;
    rep(i, 1, 4) rep(j, 1, 4) f[i][j] = cnt++;
    rep(i, 5, 8) rep(j, 1, 4) f[i][j] = f[i - 4][j];
    
    s = 0, t = 0;

    rep(i, 1, 4) rep(j, 1, 4) if (st[i][j] == '1') s |= (1 << f[i][j]);
    rep(i, 5, 8) rep(j, 1, 4) if (st[i][j] == '1') t |= (1 << f[i][j]);

    cnt = 0;

    rep(i, 1, 3) rep(j, 1, 4){ op[++cnt].x = f[i][j], op[cnt].y = f[i + 1][j];}
    rep(i, 1, 4) rep(j, 1, 3){ op[++cnt].x = f[i][j], op[cnt].y = f[i][j + 1];}

    memset(h, 0, sizeof h); h[s] = 1; Q.push({s, 0});
    
    while (!Q.empty()){
        np = Q.front(); Q.pop();
        if (np.num == t){
            printf("%d
", np.step);
            break;
        }
        rep(i, 1, cnt){
            now = np;
            x = op[i].x, y = op[i].y;
            nx = (now.num >> x) & 1, ny = (now.num >> y) & 1;
            if (nx ^ ny){
                now.num ^= (1 << x);
                now.num ^= (1 << y);
            }

            if (!h[now.num]){
                h[now.num] = 1;
                Q.push({now.num, now.step + 1});
            }
        }
    }

    return 0;

}