【最短路+状态压缩DP】 HDOJ 4856 Tunnels

先预处理出每个通道的终点到其他通道的起点的最短路，然后和 HDOJ 3247 Resource Archiver 一样，用个状态压缩DP三重循环就好了。。。顺便写了一个数据生成器，方便读者debug。。。

#include <iostream>  
#include <sstream>  
#include <algorithm>  
#include <vector>  
#include <queue>  
#include <stack>  
#include <map>  
#include <set>  
#include <bitset>  
#include <cstdio>  
#include <cstring>  
#include <cstdlib>  
#include <cmath>  
#include <climits>  
#define maxn 100005
#define eps 1e-6 
#define mod 10007 
#define INF 99999999  
#define lowbit(x) (x&(-x))  
//#define lson o<<1, L, mid  
//#define rson o<<1 | 1, mid+1, R  
typedef long long LL;
using namespace std;

char g[20][20];
int sx[20], sy[20], ex[20], ey[20];
int dis[20][20];
int dir[4][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
int vis[20][20];
int d[20][20];
int dp[maxn][20];
struct node
{
	int x, y;
	int step;
}tmp, now;
queue<node> q;
int n, m;

void bfs(int x)
{
	int i, j;
	tmp.x = ex[x], tmp.y = ey[x], tmp.step = 0;
	q.push(tmp);
	memset(vis, 0, sizeof vis);
	vis[tmp.x][tmp.y] = 1;
	for(i = 1; i <= n; i++)
		for(j = 1; j <= n; j++)
			d[i][j] = INF;
	d[tmp.x][tmp.y] = 0;
	while(!q.empty()) {
		now = q.front();
		q.pop();
		for(i = 0; i < 4; i++) {
			tmp.x = now.x + dir[i][0];
			tmp.y = now.y + dir[i][1];
			if(g[tmp.x][tmp.y] == '.' && !vis[tmp.x][tmp.y]) {
				q.push(tmp);
				d[tmp.x][tmp.y] = d[now.x][now.y] + 1;
				vis[tmp.x][tmp.y] = 1;
			}
		}
	}
	for(i = 1; i <= m; i++)
		dis[x][i] = d[sx[i]][sy[i]];
	dis[x][x] = 0;
}
void init(void)
{
	memset(dis, 0, sizeof dis);
	memset(g, '#', sizeof g);
}
void read(void)
{
	int i;
	for(i = 1; i <= n; i++)
		scanf("%s", g[i]+1), g[i][n+1] = '#';
	for(i = 1; i <= m; i++)
		scanf("%d%d%d%d", &sx[i], &sy[i], &ex[i], &ey[i]);
}
void work(void)
{
	int i, j, k, ans;
	for(i = 1; i <= m; i++)
		bfs(i);
	for(i = 0; i < (1<<m); i++)
		for(j = 1; j <= m; j++)
			dp[i][j] = INF;
	for(i = 0; i < m; i++)
		dp[1<<i][i+1] = 0;
	for(i = 0; i < (1<<m); i++)
		for(j = 1; j <= m; j++)
			if(dp[i][j] != INF)
				for(k = 1; k <= m; k++)
					if(dis[j][k] != INF && !(i&(1<<(k-1))) )
						dp[i | (1<<(k-1))][k] = min(dp[i | (1<<(k-1))][k], dp[i][j] + dis[j][k]);
	ans = INF;
	for(i = 1; i <= m; i++)
		ans = min(ans, dp[(1<<m)-1][i]);
	if(ans != INF) printf("%d\n", ans);
	else printf("-1\n");
}
int main(void)
{
	while(scanf("%d%d", &n, &m)!=EOF) {
		init();
		read();
		work();
	}
	return 0;
}

数据生成器。。。注意使用的时候可能会死循环。。。只要关闭再运行直到程序正常结束就行啦。。。每次生成10组数据。。生成完可以用上面的标程跑，和自己跑的对一下，就可以愉快地debug了。。。

#include <iostream>
#include <sstream>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <bitset>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <time.h>
#define maxn 60000
#define eps 1e-6
#define mod 10007
#define INF 99999999
#define lowbit(x) ((x)&(-(x)))
#define lson o<<1, L, mid
#define rson o<<1 | 1, mid+1, R
typedef long long LL;
using namespace std;

char g[20][20];
int main(void)
{
	//freopen ( "out.txt" , "w" , stdout ) ;
	int n, m, i, tmp1, tmp2, tmp3, tmp4, cnt, tmp, j;
	srand(time(NULL));
	for ( int _ = 1 ; _ <= 10 ; ++ _ ) {
		n = rand () % 15 + 1 ;
		m = rand () % 15 + 1 ;
		printf("%d %d\n", n, m);
		for(i = 1; i <= n; i++) {
			cnt = 1;
			while(cnt<=n) {
				tmp = rand()%2;
				if(tmp) g[i][cnt++] = '.';
				else g[i][cnt++] = '#';
			}
		}
		for(i = 1; i <= n; i++) {
			for(j = 1; j <= n; j++)
				printf("%c", g[i][j]);
			printf("\n");
		}
		for(i = 1; i <= m; i++) {
			tmp1 = rand()%n+1;
			tmp2 = rand()%n+1;
			tmp3 = rand()%n+1;
			tmp4 = rand()%n+1;
			while(g[tmp1][tmp2] != '.' || g[tmp3][tmp4] != '.') {
				tmp1 = rand()%n+1;
				tmp2 = rand()%n+1;
				tmp3 = rand()%n+1;
				tmp4 = rand()%n+1;
			}
			printf("%d %d %d %d\n", tmp1, tmp2, tmp3, tmp4);
		}
	}
}