問用一條迴路覆蓋網格里的所有空格子有幾種方法
雖然是論文的大裸入門題，但是AC跳出來還是好激動 =.=
最小表示：
#include <cstring>
#include <algorithm>
#include <iostream>
#include <vector>
#include <string>
using namespace std;
typedef __int64 lld;
const int N = 1001003;
int n,m,tot,code[15];
vector<string> s;
lld f[2][N],*cur,*nex;
struct Hash {
struct Node { lld v; int id; Node *next; };
int mod;
Node *table[N],memo[N];
void init() {
mod = 1e6+3;
tot = 0;
for (int i = 0; i < mod; i ++) table[i] = NULL;
}
int operator [] (lld x) {
int idx = x%mod;
for (Node *i = table[idx]; i ; i = i->next)
if (i->v==x) return i->id;
memo[tot] = (Node){x,tot,table[idx]};
table[idx] = &memo[tot];
return tot ++;
}
}hs;
void decode(lld x) {
for (int i = 0; i <= m; i ++)
code[i] = x>>(i*3)&7;
}
int encode() {
lld x = 0;
for (int i = m; i >= 0; i --) x = x<<3|code[i];
return hs[x];
}
void recode() {
int rt[8],cnt = 1;
memset(rt,-1,sizeof(rt)); rt[0] = 0;
for (int i = 0; i <= m; i ++) {
if (rt[code[i]]==-1) rt[code[i]] = cnt ++;
code[i] = rt[code[i]];
}
}
void show(int p) {
lld v = hs.memo[p].v;
decode(v);
for (int i = 0; i <= m; i ++) cout << code[i] << " ";
}
lld work() {
hs.init();
cur = f[0]; nex = f[1];
memset(f,0,sizeof(f));
cur[0] = 1; hs[0];
int ex,ey;
for (int i = 0; i < n; i ++)
for (int j = 0; j < m; j ++)
if (s[i][j]!='*') ex = i, ey = j;
for (int i = 0; i < n; i ++) {
for (int j = 0; j < m; j ++) {
for (int st = 0; st < tot; st ++) if (cur[st]) {
lld v = hs.memo[st].v;
decode(v);
if (s[i][j]=='*') {
if (!code[m] && !code[j]) {
nex[st] += cur[st];
}
continue;
}
if (code[m] && !code[j] && j!=m-1) {
// cout << "-" << endl;
nex[st] += cur[st];
}
if (!code[m] && code[j]) {
// cout << "1" << endl;
nex[st] += cur[st];
}
if (!code[m] && code[j] && j!=m-1) {
// cout << "1_" << endl;
code[m] = code[j];
code[j] = 0;
recode();
nex[encode()] += cur[st];
}
decode(v);
if (!code[m] && !code[j] && j!=m-1) {
// cout << "1-" << endl;
code[m] = 7;
code[j] = 7;
recode();
nex[encode()] += cur[st];
}
decode(v);
if (code[m] && !code[j]) {
// cout << "-1" << endl;
code[j] = code[m];
code[m] = 0;
recode();
nex[encode()] += cur[st];
}
decode(v);
if (code[m] && code[j]) {
// cout << "_1" << endl;
bool ok = true;
if (code[m]==code[j]) {
if (i==ex && j==ey) {
for (int k = j+1; k < m; k ++)
if (code[k]) ok = false;
} else {
ok = false;
}
}
if (ok) {
int tmp = code[m];
for (int k = 0; k <= m; k ++)
if (code[k]==tmp) code[k] = code[j];
code[m] = 0;
code[j] = 0;
recode();
nex[encode()] += cur[st];
}
}
}
swap(cur,nex);
for (int k = 0; k < tot; k ++) nex[k] = 0;
}
}
return cur[0];
}
int main() {
while (cin >> n >> m) {
s.resize(n);
for (int i = 0; i < n; i ++) cin >> s[i];
cout << work() << endl;
}
return 0;
}
括號表示：這道題上括號表示果然比最小表示快3倍不止。。雖然一部分是最小表示寫搓的原因-0-
#include <iostream>
#include <algorithm>
#include <cstring>
#include <string>
#include <vector>
using namespace std;
typedef __int64 lld;
const int INF = 0x3f3f3f3f;
const int N = 1e6+100;
int tot,n,m,code[15];
lld f[2][N],*cur,*nex;
vector<string> s;
struct Hash {
struct Node { lld v; int id; Node *next; };
Node memo[N],*table[N];
int mod;
void init() {
memset(table,0,sizeof(table));
mod = 1e6+3;
tot = 0;
}
int operator [] (lld x) {
int idx = x%mod;
for (Node *i = table[idx]; i ; i = i->next)
if (i->v==x) return i->id;
memo[tot] = (Node) {x,tot,table[idx]};
table[idx] = &memo[tot];
return tot ++;
}
}hash;
void decode(lld v) {
for (int i = 0; i <= m; i ++) code[i] = v>>(i<<1)&3;
}
lld work() {
cur = f[0]; nex = f[1];
memset(f,0,sizeof(f));
cur[0] = 1;
hash.init();
hash[0];
int ex,ey;
for (int i = 0; i < n; i ++)
for (int j = 0; j < m; j ++)
if (s[i][j]!='*') ex = i, ey = j;
for (int i = 0; i < n; i ++) {
for (int j = 0; j < m; j ++) {
for (int st = 0; st < tot; st ++) if (cur[st]) {
lld v = hash.memo[st].v,nv;
decode(v);
if (s[i][j]=='*') {
if (!code[m] && !code[j])
nex[st] += cur[st];
continue;
}
if (!code[m] && !code[j] && j!=m-1) {
nv = v^(1<<(j<<1))^(2<<(m<<1));
nex[hash[nv]] += cur[st];
}
if (!code[m] && code[j]) {
nex[st] += cur[st];
if (j!=m-1) {
nv = v^(code[j]<<(m<<1))^(code[j]<<(j<<1));
nex[hash[nv]] += cur[st];
}
}
if (code[m] && !code[j]) {
if (j!=m-1)
nex[st] += cur[st];
nv = v^(code[m]<<(j<<1))^(code[m]<<(m<<1));
nex[hash[nv]] += cur[st];
}
if (code[m] && code[j]) {
if (code[m]==2 && code[j]==1) {
nv = v^(2<<(m<<1))^(1<<(j<<1));
nex[hash[nv]] += cur[st];
} else if (code[m]==1 && code[j]==2) {
if (i==ex && j==ey) {
nv = v^(1<<(m<<1))^(2<<(j<<1));
nex[hash[nv]] += cur[st];
}
} else if (code[m]==1 && code[j]==1) {
int k,cnt = 0;
for (k = j+1; k < m; k ++) {
if (code[k]==2) cnt --;
else if (code[k]==1) cnt ++;
if (cnt==-1) break;
}
nv = v^(1<<(m<<1))^(1<<(j<<1))^(2<<(k<<1))^(1<<(k<<1));
nex[hash[nv]] += cur[st];
} else if (code[m]==2 && code[j]==2) {
int k,cnt = 0;
for (k = j-1; k >= 0; k --) {
if (code[k]==2) cnt --;
else if (code[k]==1) cnt ++;
if (cnt==1) break;
}
nv = v^(2<<(m<<1))^(2<<(j<<1))^(1<<(k<<1))^(2<<(k<<1));
nex[hash[nv]] += cur[st];
} else {
cout << "something wrong" << endl;
}
}
}
swap(cur,nex);
for (int i = 0; i < tot; i ++) nex[i] = 0;
}
}
return cur[0];
}
int main() {
while (cin >> n >> m) {
s.resize(n);
for (int i = 0; i < n; i ++) cin >> s[i];
cout << work() << endl;
}
return 0;
}