HDU 1067 Gap BFS+Hash

感觉可以用bfs暴力，一开始写了一个很暴力的bfs，hash判重，本地跑了几组数据发现至少要2s才能过，交上去估计要TLE，试探性的交了一发1A了，原来时限是10s，我看成1s了，真是逗逼。。。还一直不敢写

#include <cstdio>
#include <cstring>
#include <iostream>
#include <map>
#include <set>
#include <vector>
#include <string>
#include <queue>
#include <deque>
#include <bitset>
#include <list>
#include <cstdlib>
#include <climits>
#include <cmath>
#include <ctime>
#include <algorithm>
#include <stack>
#include <sstream>
#include <numeric>
#include <fstream>
#include <functional>

using namespace std;

#define MP make_pair
#define PB push_back
typedef long long LL;
typedef unsigned long long ULL;
typedef vector<int> VI;
typedef pair<int,int> pii;
const int INF = INT_MAX / 3;
const double eps = 1e-8;
const LL LINF = 1e17;
const double DINF = 1e60;
const int maxn = 5, maxm = 9;
const int n = 4,m = 8;
const int maxq = 65536;
int mp[maxn][maxm];

struct Node {
int data[maxn][maxm],dis;
Node(int val[maxn][maxm],int dis):dis(dis) {
for(int i = 1;i <= n;i++) {
for(int j = 1;j <= m;j++) {
data[i][j] = val[i][j];
}
}
}

Node() {
for(int i = 1;i <= n;i++) {
for(int j = 1;j < m;j++) {
data[i][j] = i * 10 + j;
}
data[i][8] = 0;
}
}

bool operator == (const Node &node) const {
for(int i = 1;i <= n;i++) {
for(int j = 1;j <= m;j++) {
if(node.data[i][j] != data[i][j]) return false;
}
}
return true;
}
};

const Node tar;

Node q[maxq], val[maxq];
int head[maxq], nxt[maxq], sz;
int qs,qe;

int gethash(const Node &now) {
int ret = 0;
for(int i = 1;i <= n;i++) {
for(int j = 1;j <= m;j++) {
ret = (ret << 6) + now.data[i][j];
}
}
return ret & (maxq - 1);
}

bool exist(const Node &now) {
int hc = gethash(now);
for(int i = head[hc];~i;i = nxt[i]) {
if(val[i] == now) return true;
}
val[sz] = now; nxt[sz] = head[hc];
head[hc] = sz++;
return false;
}

void expand(int x,int y,Node now) {
bool found = false;
int val = now.data[x][y - 1] + 1;
for(int i = 1;i <= n;i++) {
for(int j = 1;j <= m;j++) if(now.data[i][j] == val) {
now.data[i][j] = 0;
now.data[x][y] = val;
found = true;
break;
}
}
if(!found) return;
if(!exist(now)) {
now.dis++;
q[qe % maxq] = now;
qe++;
}
}

int solve() {
qs = qe = sz = 0;
q[qe++] = Node(mp,0);
memset(head,-1,sizeof(head));
while(qs < qe) {
Node now = q[qs % maxq]; qs++;
if(now == tar) return now.dis;
for(int i = 1;i <= n;i++) {
for(int j = 1;j <= m;j++) if(now.data[i][j] == 0) {
expand(i,j,now);
}
}
}
return -1;
}

int main() {
int T; scanf("%d",&T);
while(T--) {
for(int i = 1;i <= n;i++) {
for(int j = 2;j <= m;j++) {
scanf("%d",&mp[i][j]);
if(mp[i][j] % 10 == 1) {
mp[mp[i][j] / 10][1] = mp[i][j];
mp[i][j] = 0;
}
}
}
printf("%d\n",solve());
}
return 0;
}