Tony's Tour poj1739

确定了起点和终点的简单路径问题，和简单回路差不多，注意处理起点和终点以及特殊情况即可。

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <queue>
#include <algorithm>
#include <vector>
#include <cstring>
#include <stack>
#include <cctype>
#include <utility>   
#include <map>
#include <string>  
#include <climits> 
#include <set>
#include <string>    
#include <sstream>
#include <utility>   
#include <ctime>

using std::priority_queue;
using std::vector;
using std::swap;
using std::stack;
using std::sort;
using std::max;
using std::min;
using std::pair;
using std::map;
using std::string;
using std::cin;
using std::cout;
using std::set;
using std::queue;
using std::string;
using std::istringstream;
using std::make_pair;
using std::getline;
using std::greater;
using std::endl;
using std::multimap;
using std::deque;

typedef long long LL;
typedef unsigned long long ULL;
typedef pair<int, int> PAIR;
typedef multimap<int, int> MMAP;

const int MAXN(1000010);
const int MAXM(10010);
const int MAXE(10010);
const int HSIZE(13131);
const int SIGMA_SIZE(26);
const int MAXH(19);
const int INFI(2000000000);
const int MOD(100000000);
const ULL BASE(31);
const LL LIM(10000000);
const int INV(-10000);

struct HASH_MAP
{
	int first[HSIZE], next[MAXN];
	int state[MAXN];
	LL value[MAXN];
	int  size;
	void init()
	{
		memset(first, -1, sizeof(first));
		size = 0;
	}

	void insert(int ts, LL tv)
	{
		int h = ts%HSIZE;
		for(int i = first[h]; ~i; i = next[i])
			if(state[i] == ts)
			{
				value[i] += tv;
				return;
			}
		state[size] = ts;
		value[size] = tv;
		next[size] = first[h];
		first[h] = size++;
	}
}hm[2];

HASH_MAP *cur, *last;
char mp[10][10];
int code[10], Num[8];

void decode(int m, int ts)
{
	for(int i = 0; i <= m; ++i)
	{
		code[i] = ts&7;
		ts >>= 3;
	}
}

int encode(int m)
{
	int ret = 0, cnt = 0;
	memset(Num, -1, sizeof(Num));
	for(int i = m; i >= 0; --i)
		if(code[i] == 0)
			ret <<= 3;
		else
		{
			if(Num[code[i]] < 0) Num[code[i]] = ++cnt;
			ret = (ret << 3)|Num[code[i]];
		}
	return ret;
}

int si, sj, ei, ej;

inline bool startgrid(int i, int j){ return i == si && j == sj;}
inline bool endgrid(int i, int j){ return i == ei && j == ej;}

void updata(int i, int j, int m, LL tv)
{
	int up = (i == 0)? 0: code[j+1];
	int left = (j == 0)? 0: code[j];
	if(mp[i][j] == '#')
	{
		if(up == 0 && left == 0)
		{
			code[j] = code[j+1] = 0;
			cur->insert(encode(m), tv);
		}
		return;
	}
	if(up == 0 && left == 0)
	{
		if(j == m-1) return;
		if(startgrid(i, j)) 
		{
			code[j] = 0;
			code[j+1] = 7;
			cur->insert(encode(m), tv);
			return;
		}
		code[j] = code[j+1] = 7;
		cur->insert(encode(m), tv);
	}
	else
		if(up == 0 || left == 0)
		{
			if(startgrid(i, j) || endgrid(i, j))
			{
				code[j] = code[j+1] = 0;
				cur->insert(encode(m), tv);
				return;
			}
			code[j] = left+up;
			code[j+1] = 0;
			cur->insert(encode(m), tv);
			if(j == m-1) return;
			code[j] = 0;
			code[j+1] = left+up;
			cur->insert(encode(m), tv);
		}
		else
			if(up != left)
			{
				if(endgrid(i, j)) return;
				for(int k = 0; k <= m; ++k)
					if(code[k] == up) code[k] = left;
				code[j] = code[j+1] = 0;
				cur->insert(encode(m), tv);
			}
}

void solve(int n, int m)
{
	cur = hm;
	last = hm+1;
	last->init();
	last->insert(0, 1);
	for(int i = 0; i < n; ++i)
		for(int j = 0; j < m; ++j)
		{
			cur->init();
			int sz = last->size;
			for(int k = 0; k < sz; ++k)
			{
				decode(m, last->state[k]);
				if(j == 0)
					for(int k2 = m; k2 >= 1; --k2)
						code[k2] = code[k2-1];
				updata(i, j, m, last->value[k]);
			}
			swap(cur, last);
		}
	LL ans = 0;
	for(int i = 0; i < last->size; ++i)
		if(last->state[i] == 0)
		{
			ans = last->value[i];
			break;
		}
	printf("%I64d\n", ans);
}

int main()
{
	int n, m;
	while(scanf("%d%d", &n, &m), n || m)
	{
		for(int i = 0; i < n; ++i)
			scanf("%s", mp[i]);
		si = n-1;
		sj = 0;
		ei = n-1;
		ej = m-1;
		if(mp[si][sj] == '#' || mp[ei][ej] == '#')
		{
			printf("0\n");
			continue;
		}
		if(n == 1 && m == 1)
		{
			printf("1\n");
			continue;
		}
		solve(n, m);
	}
	return 0;
}