Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 2014 Accepted Submission(s): 615

/*
hdu 4568 Hunter 最短路+dp
problem:
给你一个n*m的地图,每走一个格子会有一定的花费.求拿到所有宝藏的最小花费
solve:
想了很久感觉没什么思路TAT
后来看别人题解可以把这个问题转换一下.
因为总共只有13个宝藏,所以我们可以处理出每个宝藏之间的最短路(即最小花费).
在弄出每个宝藏到边界的最小距离. 那么就可以看成13个点的图.找出遍历所有点的最小花费
而13个点的状态可以用二进制保存,所以dp就好.
hhh-2016-08-26 21:43:38
*/
#pragma comment(linker,"/STACK:124000000,124000000")
#include <algorithm>
#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <vector>
#include <math.h>
#include <queue>
#include <map>
#define lson i<<1
#define rson i<<1|1
#define ll long long
#define clr(a,b) memset(a,b,sizeof(a))
#define scanfi(a) scanf("%d",&a)
#define scanfl(a) scanf("%I64d",&a)
#define key_val ch[ch[root][1]][0]
#define inf 0x3f3f3f3f
using namespace std;
const ll mod = 1e9+7;
const int maxn = 220;
struct NODE
{
int id,len;
NODE() {}
NODE(int i,int d):id(i),len(d) {}
bool operator <(const NODE &a) const
{
return len > a.len;
}
};
int n,m;
int dx[4]= {-1,1,0,0};
int dy[4]= {0,0,-1,1};
int from[maxn][maxn];
int vis[maxn*maxn],tmap[maxn][maxn],tp[maxn][maxn],out[maxn];
int pos[maxn*maxn],dis[maxn*maxn];
void dij(int st,int fp)
{
memset(vis,0,sizeof(vis));
memset(dis,inf,sizeof(dis));
priority_queue<NODE> q;
q.push(NODE(st,0));
dis[st] = 0;
while(!q.empty())
{
NODE t = q.top();
q.pop();
int cur = t.id;
if(vis[cur]) continue;
vis[cur] = 1;
int x = cur/m,y = cur%m;
if(tp[x][y] != -1)
from[fp][tp[x][y]] = dis[cur];
if(x == n-1 || x == 0 || y == m-1 || y == 0)
{
out[fp]= min(out[fp],dis[cur]);
}
for(int i = 0; i < 4; i++)
{
int tx = x + dx[i];
int ty = y + dy[i];
if(tmap[tx][ty] == -1) continue;
if(tx >= n || tx < 0 || ty >= m || ty < 0)
continue;
if(dis[tx*m + ty] > dis[cur] + tmap[tx][ty])
{
dis[tx*m + ty] = dis[cur] + tmap[tx][ty];
q.push(NODE(tx*m + ty, dis[tx*m + ty] ));
}
}
}
return ;
}
int dp[20][1 << 14];
void init()
{
memset(from,0,sizeof(from));
memset(out,inf,sizeof(out));
memset(tp,-1,sizeof(tp));
memset(dp,inf,sizeof(dp));
}
int main()
{
// freopen("in.txt","r",stdin);
int T,x,y;
scanf("%d",&T);
while(T--)
{
init();
scanfi(n),scanfi(m);
for(int i = 0; i < n; i++)
{
for(int j = 0; j < m; j++)
scanfi(tmap[i][j]);
}
int q;
scanfi(q);
for(int i = 0; i < q; i++)
{
scanfi(x),scanfi(y);
tp[x][y] = i;
pos[i] = x*m + y;
}
for(int i = 0; i < q; i++)
{
from[i][i] = 0;
dij(pos[i],i);
}
for(int i = 0; i < q; i++)
{
dp[i][1 << i] = out[i]+tmap[pos[i]/m][pos[i]%m];
}
// for(int i = 0;i < q;i++)
// {
// cout << "i"<<i<<":" <<out[i] <<endl;
// for(int j = i;j < q;j++)
// cout << i <<"----"<<j<<" :" <<from[i][j]<<endl;
// }
// cout <<endl;
for(int i = 0; i < (1 << q); i++)
{
for(int j = 0; j < q; j++)
{
if( ((1 << j) & i) && i != (1 << j))
{
for(int k = 0; k < q; k++)
{
if( (i & (1 << k)) && j != k && i != (1<< k))
dp[j][i] = min(dp[k][i-(1 << j)]+from[k][j],dp[j][i]);
}
}
}
}
int ans = inf;
for(int i = 0; i < q; i++)
{
ans = min(ans,dp[i][(1<<q)-1] + out[i]);
// cout << ans <<endl;
}
printf("%d\n",ans);
}
return 0;
}
原文:http://www.cnblogs.com/Przz/p/5812369.html